SUMMARY

This summary provides a brief overview of information contained elsewhere in this prospectus. You should read the entire prospectus carefully, including the historical combined and consolidated financial statements, the pro forma combined financial statements and the related notes included elsewhere herein before investing in our common units. Unless indicated otherwise, the information presented in this prospectus assumes (1) an initial public offering price of $         per common unit and (2) that the underwriters do not exercise their option to purchase additional common units. You should read “Risk Factors” beginning on page 26 for more information about important risks that you should consider carefully before investing in our common units. We include a glossary of some of the terms used in this prospectus as Appendix B.

Except as otherwise set forth in the prospectus, all references in this prospectus to “our,” “we,” the “partnership,” “us” and like terms, when used with respect to periods prior to May 1, 2013, refer to the entities comprising CenterPoint Energy’s interstate pipelines and field services reportable business segments, and when used with respect to periods on and after May 1, 2013, refer to Enable Midstream Partners, LP and its subsidiaries. For a description of the transactions entered into in connection with the formation of our partnership on May 1, 2013, please read “—Formation Transactions and Partnership Structure.” References to “Enable GP” or our “general partner” are to Enable GP, LLC, a Delaware limited liability company and our general partner; references to “CenterPoint Energy” are to CenterPoint Energy, Inc., a Texas corporation, and its subsidiaries, other than us; references to “OGE Energy” are to OGE Energy Corp., an Oklahoma corporation, and its subsidiaries, other than us; references to our “sponsors” are to CenterPoint Energy and OGE Energy; and references to “ArcLight” are to ArcLight Capital Partners, LLC, a Delaware limited liability company, its affiliated entities, ArcLight Energy Partners Fund V, L.P., ArcLight Energy Partners Fund IV, L.P., Bronco Midstream Partners, L.P., Bronco Midstream Infrastructure LLC and Enogex Holdings LLC, and their respective general partners and subsidiaries.

ENABLE MIDSTREAM PARTNERS, LP

Our Business

We are a large-scale, growth-oriented limited partnership formed to own, operate and develop strategically located natural gas and crude oil infrastructure assets. We serve key current and emerging production areas in the United States, including several premier shale resource plays and local and regional end-user markets in the United States. Our assets and operations are organized into two business segments: (i) gathering and processing, which primarily provides natural gas gathering, processing and fractionation services and crude oil gathering for our producer customers, and (ii) transportation and storage, which provides interstate and intrastate natural gas pipeline transportation and storage service to natural gas producers, utilities and industrial customers. In both business segments, we generate a substantial portion of our gross margin under long-term, fee-based agreements that minimize our direct exposure to commodity price fluctuations.

Our natural gas gathering and processing assets are strategically located in four states and serve natural gas production from shale developments, which we refer to as unconventional shale resource plays, in some of the most productive regions of the Anadarko, Arkoma and Ark-La-Tex basins. These basins have experienced a strong increase in investment and drilling activity by exploration and production companies in recent years. We also own an emerging crude oil gathering business in the Bakken shale formation of the Williston Basin that commenced initial operations in November 2013. We are continuing to construct additional crude oil gathering capacity in this area. Our natural gas transportation and storage assets extend from western Oklahoma and the Texas Panhandle to Alabama and from Louisiana to Illinois.

Upon our formation in May 2013 as a limited partnership among OGE Energy, CenterPoint Energy and ArcLight, we became one of the largest midstream partnerships in the United States based on total assets. As of

December 31, 2013, our portfolio of energy infrastructure assets included approximately 11,000 miles of gathering pipelines, 12 major processing plants with approximately 2.1 Bcf/d of processing capacity, approximately 7,900 miles of interstate pipelines (including Southeast Supply Header, LLC, or SESH, in which we own a 24.95% interest), approximately 2,300 miles of intrastate pipelines and eight storage facilities comprising 86.5 Bcf of storage capacity. We believe our scale benefits our customers by providing them with fully integrated midstream services and improved access from the wellhead to the marketplace. In addition, we believe our scale and scope will position us to be more competitive in developing new energy infrastructure assets and adding complementary services and business lines.

From the year ended December 31, 2011 through the year ended December 31, 2013, on a pro forma basis, we grew the volume of gas processed on our systems by 61%. We expect to continue to grow our business by providing midstream services to our customers’ rapidly growing upstream development projects. We expect our customers’ activity in the basins in which we operate to result in higher throughput on our systems and additional organic growth opportunities to expand the capacity and utilization of our assets. We also expect to grow our business and distributable cash flow by developing new energy infrastructure projects to support new and existing customers as they expand beyond our current footprint, as well as through third-party acquisitions. For the years ended December 31, 2011, 2012 and 2013, on a pro forma basis, we invested $798 million, $912 million and $571 million, respectively, in expansion capital expenditures. We expect that our expansion capital expenditures will be $533 million for the twelve months ending March 31, 2015.

We believe that our contractual arrangements provide a strong platform to support established operations and future organic growth. For the year ended December 31, 2013, on a pro forma basis, approximately 76% of our gross margin was generated from contracts that are fee-based, and approximately 50% of our gross margin was attributable to firm contracts or contracts with minimum volume commitment features.

For the year ended December 31, 2013, on a pro forma basis, we generated $1,322 million of gross margin, $779 million of Adjusted EBITDA and $454 million of net income. Gross margin and Adjusted EBITDA are non-GAAP financial measures. For definitions of gross margin and Adjusted EBITDA and a reconciliation to their most directly comparable financial measures calculated in accordance with generally accepted accounting principles in the United States, or GAAP, please read “—Summary Historical and Pro Forma Financial and Operating Data—Non-GAAP Financial Measures.”

Gathering and Processing. We provide gathering, processing, treating, compression, dehydration and natural gas liquids (NGLs) fractionation for natural gas producers. Our gathering and processing assets are strategically located in established and actively developing basins in the United States and are interconnected with our interstate and intrastate pipelines and with third-party pipelines, which provides our customers with the benefits of a flexible and efficient transportation and storage system. On a pro forma basis for the year ended December 31, 2013, our top customers by volumes gathered were affiliates of Encana Corporation (Encana), Shell Oil Corporation (Shell), Exxon Mobil Corporation (Exxon), Chesapeake Energy Corporation (Chesapeake), Apache Corporation (Apache), Continental Resources, Inc. (Continental), QEP Energy Company (QEP), Devon Energy Production Company LP (Devon), BP America Production Company (BP) and Samson Resources Company (Samson).

The following table sets forth certain information regarding our gathering and processing assets on a pro forma basis as of or for the year ended December 31, 2013:

Six of our processing plants in the Anadarko basin are interconnected via our large-diameter, rich gas gathering system in western Oklahoma, which spans 18 counties and has approximately 1.2 Bcf/d of processing capacity. Our 4.7 million gross acres of acreage dedications in the Anadarko basin area are served by this system, which we refer to as our “super-header” system. We have configured this system to optimize the flow of natural gas and the utilization of the processing plants connected to it, which we believe provides us with strategic growth opportunities. We have made investments to expand the super-header system, including our newest plant located in Custer County, Oklahoma (the McClure Plant) that was placed in service in December 2013. The McClure Plant increased our natural gas processing capacity in the basin by over 15%, providing an additional 200 MMcf/d of natural gas processing capacity. We expect to continue to grow the capacity of the super-header system through the planned addition of another new cryogenic processing plant and related gathering pipelines. This plant, which will be located in Grady County, Oklahoma (the Bradley Plant), will provide an additional 200 MMcf/d of processing capacity and is expected to be completed in the first quarter of 2015.

We believe our contract structures provide us with stable cash flows in our major operating basins. For the year ended December 31, 2013, on a pro forma basis, we generated 61% of our gathering and processing gross margin under long-term, fee-based agreements, and of this fee-based margin, approximately 38% was attributable to gathering and processing contracts containing minimum volume commitment features. Under our minimum volume commitment contracts, our customers commit to ship a minimum annual volume of natural gas on our gathering system, or, in lieu of shipping such volumes, to pay us periodically as if that minimum amount had been shipped. As of December 31, 2013, we had minimum volume commitments in lean natural gas developments of 1.6 Bcf/d with a weighted average remaining term of over nine years. We also have an emerging crude oil gathering business in the Bakken shale formation. Our current operations in the Bakken have a similar minimum volume commitment contract structure that we believe will provide us with an additional source of stable cash flows. Under our acreage dedication contracts, our customers are generally required to deliver all of their production within the dedicated area to our gathering system over the period of the contract. As of December 31, 2013, we had acreage dedications in rich natural gas developments covering more than 5.7 million acres that generally have long lived reserves with a weighted average remaining term of approximately nine years. As of December 31, 2013, our gathering and processing contracts for our top ten natural gas producer customers, which accounted for approximately 75% of our gathered volumes for the year ended December 31, 2013, on a pro forma basis, had a volume-weighted average remaining term of approximately nine years.

For the year ended December 31, 2013, on a pro forma basis, our gathering and processing business segment generated $762 million of gross margin and $467 million of Adjusted EBITDA.

Transportation and Storage. Our natural gas transportation and storage business segment consists of our interstate pipelines, our intrastate pipelines and our storage assets. We provide pipeline takeaway capacity for natural gas producers from supply basins to market hubs and critical natural gas supply for industrial end users and utilities, such as local distribution companies, or LDCs, and power generators. Our interstate pipeline system, including SESH, includes approximately 7,900 miles of transportation pipelines and extends from western Oklahoma and the Texas Panhandle to Alabama and from Louisiana to Illinois. Our eight storage facilities in Oklahoma, Louisiana and Illinois have 86.5 Bcf of storage capacity and strategically complement our pipeline systems.

The following table sets forth certain information regarding our transportation and storage assets as of December 31, 2013:

We generate revenue primarily by charging demand fees pursuant to applicable tariffs for the transportation and storage of natural gas on our system. On a pro forma basis, we generated 96% of our transportation and storage gross margin under fee-based agreements with a weighted average remaining contract life of over four years as of December 31, 2013. Demand-based margin for this period represented 89% of the fee-based margin, on a pro forma basis. We generally do not take ownership of the natural gas that we transport and store.

For the year ended December 31, 2013, on a pro forma basis, our top customers by gross margin were affiliates of CenterPoint Energy, Laclede Group (Laclede), OGE Energy, American Electric Power Company, Inc. (AEP) and Exxon. Our transportation and storage assets were designed and built to serve affiliates of CenterPoint Energy, Laclede, OGE Energy and AEP and are competitively positioned to serve other large natural gas and electric utility companies, such as Ameren Corporation (Ameren) and Entergy Corporation (Entergy).

For the year ended December 31, 2013, on a pro forma basis, our transportation and storage business segment generated $562 million of gross margin and $313 million of Adjusted EBITDA.

Business Strategies

Our primary business objective is to practice operational excellence and to grow our business responsibly, enabling us to increase the amount of cash distributions we make to our unitholders over time while maintaining our financial stability. We intend to accomplish this objective by executing the strategies listed below:

Competitive Strengths

We believe that we are well positioned to execute our business strategies successfully because of the following competitive strengths:

Our Relationship with OGE Energy and CenterPoint Energy

OGE Energy and CenterPoint Energy are aligned with us to grow our distributions. Following the completion of this offering, OGE Energy and CenterPoint Energy will retain a significant interest in us through their approximate                 % and                 % limited partner interests in us, respectively. OGE Energy and CenterPoint Energy will each own 50% of the management rights of our general partner, which holds all of our incentive distribution rights. In addition, OGE Energy and CenterPoint Energy own 60% and 40%, respectively, of the economic rights in our general partner.

OGE Energy (NYSE: OGE) is the parent company of Oklahoma Gas and Electric Company, or OG&E, a regulated electric utility serving approximately 805,000 customers in a service territory spanning 30,000 square miles in Oklahoma and western Arkansas. OG&E furnishes retail electric service in 268 communities and their contiguous rural and suburban areas. OG&E’s service area includes Oklahoma City, Oklahoma and Fort Smith, Arkansas, the second largest city in that state. Of the 268 communities that OG&E serves, 242 are located in Oklahoma and 26 are located in Arkansas. As of December 31, 2013, OGE Energy had total assets of $9.1 billion and a market capitalization of $6.7 billion.

CenterPoint Energy (NYSE: CNP) is a public utility holding company whose indirect wholly owned subsidiaries include (i) CenterPoint Energy Houston Electric, LLC, which provides electric transmission and distribution services to retail electric providers serving over two million metered customers in a 5,000-square-mile area of the Texas Gulf Coast that has a population of approximately six million people and includes the city of Houston; and (ii) CenterPoint Energy Resources Corp., which owns and operates natural gas distribution systems serving more than three million customers in six states, including customers in the metropolitan areas of Houston, Texas; Minneapolis, Minnesota; Little Rock, Arkansas; Shreveport, Louisiana; Biloxi, Mississippi; and Lawton, Oklahoma. As of December 31, 2013, CenterPoint Energy had total assets of $21.9 billion and a market capitalization of $9.9 billion.

Our sponsors are also significant customers of our transportation and storage business segment and continue to own and operate a substantial portfolio of energy assets. For the years ended December 31, 2013 and 2012, on a pro forma basis, approximately 4% of our total gross margin was derived from contracts servicing electric power generation with OGE Energy. For the years ended December 31, 2013 and 2012, on a pro forma basis, approximately 7% of our total gross margin was derived from contracts servicing LDCs owned by CenterPoint Energy.

Our sponsors entered into a number of agreements in connection with our formation. Please read “Certain Relationships and Related Party Transactions” for a detailed description of these agreements, as well as other agreements affecting us and our sponsors. Although we believe our relationships with OGE Energy and CenterPoint Energy are positive attributes, there can be no assurance that we will benefit from these relationships.

RISK FACTORS

An investment in our common units involves risks associated with our business, our regulatory and legal matters, our limited partnership structure and the tax characteristics of our common units. You should carefully consider the risks described in “Risk Factors” beginning on page 26 of this prospectus and the other information in this prospectus before deciding whether to invest in our common units.

Risks Related to Our Business

Risks Related to an Investment in Us

Tax Risks to Common Unitholders

FORMATION TRANSACTIONS AND PARTNERSHIP STRUCTURE

We were formed in May 2013 by affiliates of CenterPoint Energy, OGE Energy and ArcLight to own, operate and develop a diversified portfolio of complementary midstream businesses previously operated by OGE Energy and CenterPoint Energy. Pursuant to a master formation agreement among our sponsors and ArcLight, the following transactions, which we refer to as our formation transactions, occurred in connection with our formation:

As consideration for the contribution of these assets and agreements, we issued 291,002,583 common units to CenterPoint Energy, 141,956,176 common units to OGE Energy and 65,908,224 common units to ArcLight. We also issued a non-economic general partner interest and our incentive distribution rights to Enable GP. Enable GP is equally controlled by CenterPoint Energy and OGE Energy, with each owning 50% of the management rights. Enable GP holds all of our incentive distribution rights, 40% of which are allocated to CenterPoint Energy and 60% of which are allocated to OGE Energy. In connection with this offering,                 of CenterPoint Energy’s common units and                  of OGE Energy’s common units will be converted into subordinated units.

We also entered into a number of agreements with our sponsors in connection with our formation. These agreements included an agreement with respect to the transfer of CenterPoint Energy’s remaining 25.05% interest in SESH to us, an omnibus agreement, certain services and employment agreements and tax sharing agreements. In addition, upon our formation, we entered into our $1.05 billion three-year term loan facility and our $1.4 billion five-year revolving credit facility.

ORGANIZATIONAL STRUCTURE

The diagram below depicts a simplified organization and ownership chart after giving effect to the offering. After giving effect to this offering, our units will be held as follows:

MANAGEMENT OF ENABLE MIDSTREAM PARTNERS, LP

Enable GP, LLC, our general partner, will manage our business and operations. The board of directors and executive officers of our general partner will oversee our operations and make decisions on our behalf. Certain officers and directors of OGE Energy and CenterPoint also serve as executive officers or directors of our general partner.

Unlike shareholders in a publicly traded corporation, our common unitholders will not be entitled to elect our general partner or its directors. OGE Energy and CenterPoint Energy each have the right to designate two members of the board of directors of our general partner, with any additional members of our board of directors being designated collectively by OGE Energy and CenterPoint Energy. At the closing of this offering, our general partner will have one director who is independent as defined under the independence standards established by the New York Stock Exchange, or NYSE. OGE Energy and CenterPoint Energy will appoint one additional independent director within 90 days of the date of this prospectus and a third independent director within 12 months of the date of this prospectus. For information about the executive officers and directors of our general partner, please read “Management.”

SUMMARY OF CONFLICTS OF INTEREST AND FIDUCIARY DUTIES

Our general partner has a duty to manage our partnership in a manner it subjectively believes is in our best interests. However, the officers and directors of our general partner also have duties to manage our general partner in a manner beneficial to its owners, OGE Energy and CenterPoint Energy. Additionally, certain of our executive officers and initial directors are officers and/or directors of OGE Energy or CenterPoint Energy. As a result, conflicts of interest may arise in the future between us and our common unitholders, on the one hand, and OGE Energy and CenterPoint Energy and our general partner, on the other hand. For a more detailed description of the conflicts of interest of our general partner, please read “Risk Factors—Risks Related to an Investment in Us” and “Conflicts of Interest and Fiduciary Duties—Conflicts of Interest.”

Delaware law provides that Delaware limited partnerships may, in their partnership agreements, expand, restrict or eliminate the fiduciary duties owed by the general partner to limited partners and the partnership. Pursuant to these provisions, our partnership agreement contains various provisions replacing the fiduciary duties that would otherwise be owed by our general partner with contractual standards governing the duties of the general partner and the methods of resolving conflicts of interest. The effect of these provisions is to restrict the remedies available to our common unitholders for actions taken by our general partner that might otherwise constitute breaches of fiduciary duty. Our partnership agreement also provides that, subject to the provisions contained in the omnibus agreement, affiliates of our general partner, including OGE Energy and CenterPoint Energy and their other subsidiaries and affiliates, are permitted to compete with us. We may enter into additional agreements in the future with OGE Energy and CenterPoint Energy relating to the purchase of additional assets, the provision of certain services to us by OGE Energy or CenterPoint Energy and other matters. In the performance of their obligations under these agreements, OGE Energy and CenterPoint Energy and their subsidiaries are not held to a fiduciary duty standard of care to us, our general partner or our limited partners, but rather to the standard of care specified in these agreements. By purchasing a common unit, the purchaser agrees to be bound by the terms of our partnership agreement, and each common unitholder is treated as having consented to various actions and potential conflicts of interest contemplated in the partnership agreement that might otherwise be considered a breach of fiduciary or other duties under applicable state law.

For a description of our other relationships with our affiliates, please read “Certain Relationships and Related Party Transactions.”

PRINCIPAL EXECUTIVE OFFICES AND INTERNET ADDRESS

Our principal executive offices are located at One Leadership Square, 211 North Robinson Avenue, Suite 950, Oklahoma City, Oklahoma 73102, and our telephone number is (405) 525-7788. Our website is located at www.enablemidstream.com. Information on our website or any other website is not incorporated by reference into this prospectus and does not constitute a part of this prospectus. We expect to make our periodic reports and other information filed with or furnished to the Securities and Exchange Commission, or the SEC, available, free of charge, on our website, as soon as reasonably practicable after those reports and other information are electronically filed with or furnished to the SEC.

THE OFFERING

SUMMARY HISTORICAL AND PRO FORMA FINANCIAL AND OPERATING DATA

The following tables set forth, for the periods and as of the dates indicated, the summary historical financial and operating data of Enable Midstream Partners, LP, which is derived from the historical books and records of the partnership, the summary historical financial and operating data of Enogex, which is derived from the historical books and records of Enogex, and the pro forma financial and operating data of Enable Midstream Partners, LP. On May 1, 2013 (formation), OGE Energy and ArcLight indirectly contributed 100% of the equity interests in Enogex to the partnership in exchange for common units and, for OGE Energy only, interests in our general partner. The transaction was considered a business combination for accounting purposes, with the partnership considered the acquirer of Enogex. Subsequent to May 1, 2013, the financial and operating data of the partnership are consolidated to reflect the acquisition of Enogex and the retention of certain assets and liabilities by CenterPoint Energy. The following tables should be read together with, and are qualified in their entirety by reference to, the historical and unaudited pro forma and supplemental pro forma combined and consolidated financial statements, as applicable, and the accompanying notes included elsewhere in this prospectus.

The summary historical financial and operating data of Enable Midstream Partners, LP for the years ended December 31, 2013, 2012 and 2011 and balance sheet data as of December 31, 2013 and 2012 is derived from and should be read in conjunction with the audited historical combined and consolidated financial statements of the partnership included elsewhere in this prospectus. The operating data for all periods is unaudited. The following table should be read together with “Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

The summary historical financial and operating data of Enogex for the years ended December 31, 2012 and 2011 and balance sheet data as of December 31, 2012 and 2011 is derived from and should be read in conjunction with the audited historical consolidated financial statements of Enogex included elsewhere in this prospectus. The operating data for all periods is unaudited.

The summary unaudited pro forma financial and operating data is derived from and should be read in conjunction with the unaudited pro forma and supplemental pro forma combined financial statements of Enable Midstream Partners, LP included elsewhere in this prospectus. The pro forma balance sheet assumes that the offering occurred as of December 31, 2013 and the pro forma condensed combined statements of income for the years ended December 31, 2013 and 2012 assume that our formation transactions and this offering, with respect to unit and per unit information, occurred as of January 1, 2013 and 2012, respectively. These transactions include, and the pro forma financial data gives effect to, the following:

The pro forma financial data does not give effect to the estimated $3 million in incremental annual operation and maintenance expense we expect to incur as a result of being a publicly traded partnership. The pro forma financial data does not give effect to any potential cost savings or other operating efficiencies from the integration of the partnership and Enogex. The pro forma financial data does not reflect adjustments for the execution of service agreements with CenterPoint Energy and OGE Energy upon formation since the costs under these service agreements were previously incurred by the partnership and Enogex on a similar basis. The pro forma financial data does not adjust for acquisition related costs since the partnership incurred no acquisition related costs in the Combined and Consolidated Statement of Income during any period presented based upon the terms in the master formation agreement. For a description of the step acquisition gain, please refer to “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Results of Operations—Pro Forma.”

The following tables include the financial measures of gross margin, which we use as a measure of performance, Adjusted EBITDA, which we use as a measure of performance and liquidity, and distributable cash flow, which we use as a measure of liquidity. Gross margin, Adjusted EBITDA and distributable cash flow are not calculated and presented in accordance with GAAP. We define gross margin as total revenues minus cost of goods sold, excluding depreciation and amortization. We define Adjusted EBITDA as net income from continuing operations before interest expense, income tax expense, depreciation and amortization expense and certain other items management believes affect the comparability of operating results. For a reconciliation of gross margin, Adjusted EBITDA and distributable cash flow to their most directly comparable financial measures calculated and presented in accordance with GAAP, please see “—Non-GAAP Financial Measures.”

NON-GAAP FINANCIAL MEASURES

We define gross margin as total revenues minus cost of goods sold, excluding depreciation and amortization. We define Adjusted EBITDA as net income from continuing operations before interest expense, income tax expense, depreciation and amortization expense and certain other items management believes affect the comparability of operating results. The economic substance behind the use of Adjusted EBITDA is to measure the ability of our assets to generate cash sufficient to pay interest costs, support our indebtedness and make distributions to our investors. For a discussion of distributable cash flow, please see “Cash Distribution Policy and Restrictions on Distributions—Unaudited Pro Forma Distributable Cash Flow for the Year Ended December 31, 2013.” Gross margin, Adjusted EBITDA and distributable cash flow are supplemental financial measures that management and external users of our financial statements, such as industry analysts, investors, lenders and rating agencies may use, to assess:

We believe that the presentation of gross margin, Adjusted EBITDA and distributable cash flow provides information useful to investors in assessing our financial condition and results of operations. Gross margin, Adjusted EBITDA and distributable cash flow should not be considered as alternatives to net income, operating income, revenue, cash from operations or any other measure of financial performance or liquidity presented in accordance with GAAP. Gross margin, Adjusted EBITDA and distributable cash flow have important limitations as an analytical tool because they exclude some but not all items that affect the most directly comparable GAAP measures. Additionally, because gross margin, Adjusted EBITDA and distributable cash flow may be defined differently by other companies in our industry, our definitions of gross margin, Adjusted EBITDA and distributable cash flow may not be comparable to similarly titled measures of other companies, thereby diminishing their utility.

The following table presents a reconciliation of (i) gross margin to revenues, (ii) Adjusted EBITDA and distributable cash flow to net income attributable to controlling interest and (iii) Adjusted EBITDA to net cash provided by operating activities, in each case, the most directly comparable GAAP financial measures, on a historical basis and pro forma basis, as applicable, for each of the periods indicated.