ONEOK INC /NEW/

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a)

of the Securities Exchange Act of 1934

Check the appropriate box:

ONEOK, Inc.

(Name of Registrant as Specified In Its Charter)

NOT APPLICABLE

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

Dear Shareholder

At ONEOK, our commitment to responsible operations, disciplined and intentional growth and meaningful engagements with our stakeholders has remained paramount throughout our long history. We continue to embrace our philosophy of continuous improvement by working to enhance our operations in every area.

You are cordially invited to attend the annual meeting of shareholders of ONEOK, Inc., which will be held at 9:00 a.m. Central Daylight Time on

Wednesday, May 20, 2026. Our annual meeting will be held, as in prior years, as a virtual meeting only and will be conducted via live webcast. You will not be able to attend the annual meeting in person.

By continuing to hold our annual meeting virtually, our shareholders will be able to join us from any location around the world, enabling increased shareholder attendance and participation, providing a cost savings to both us and our shareholders while contributing to our sustainability efforts by reducing the environmental footprint of our annual meeting.

Information on how to virtually attend and participate in the annual meeting online via the live webcast platform is provided under “About the 2026 Annual Meeting” in the accompanying proxy statement.

ANNUAL MEETING

The matters to be considered and voted on at the meeting are set forth in the accompanying notice of the annual meeting and are described in the accompanying proxy statement. A report on our 2025 performance will be presented at the meeting.

VOTING

We look forward to welcoming as many of our shareholders as possible to the live webcast of our annual meeting. We know, however, that most of our shareholders will be unable to attend. Therefore, proxies are being solicited so that each shareholder has an opportunity to vote by proxy. You can authorize a proxy over the internet or by telephone or, if you received paper copies of these materials, by signing, dating and returning the enclosed proxy card in the enclosed envelope, which requires no postage if mailed in the United States. If you previously received our Notice of Internet Availability of Proxy Materials, instructions regarding how you can vote are contained in that notice. Further instructions for using all of these convenient services are also included in the accompanying proxy statement.

If your shares are held through a broker or similar person, unless you provide them with voting instructions, your shares will not be voted in the election of directors or in certain other important proposals as described in the accompanying proxy statement. Consequently, please provide your voting instructions to your broker or similar person in a timely manner to ensure that your shares will bevoted.

Regardless of the number of shares you own, your vote is important. I urge you to submit your proxy or voting instructions as soon as possible so that you can be sure your shares will be voted.

Thank you for your investment in ONEOK and your continued support.

Very truly yours,

Julie H. EdwardsBoard Chair

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Notice of 2026 Annual Meeting of Shareholders

Items of Business

We will also consider and vote on such other business as may come properly before the meeting or any adjournment or postponement of the meeting.

These matters are described more fully in the accompanying proxy statement.

YOUR VOTE IS IMPORTANT

The vote of every shareholder is important. The Board of Directors appreciates the cooperation of shareholders in directing proxies to vote at the meeting. To make it easier for you to vote, internet and telephone voting are available. If you previously received our Notice of Internet Availability of Proxy Materials, instructions regarding how you can vote are contained in that notice. If you received a proxy card, you may vote by mail by completing your proxy card and returning it in the enclosed, postage-paid envelope. Further instructions describing how to use these convenient voting methods are also included in the accompanying proxy statement. You may revoke your proxy at any time by following the procedures set forth in the accompanying proxy statement.

Whether or not you expect to virtually attend the meeting, we urge you to vote your shares at your earliest convenience. This will ensure the presence of a quorum at the meeting. Voting your shares promptly, via the internet, by telephone, or if you received a proxy card, by signing, dating and returning the enclosed proxy card will save us the expense of additional solicitation.

By order of the Board of Directors,

Sarah M. Rechter

Secretary

Tulsa, Oklahoma

Time and DateMay 20, 20269:00 a.m. Central Daylight Time

Virtual MeetingRegister online atwww.proxydocs.com/oke

Record DateMarch 23, 2026Only shareholders of record at the close of business on the record date are entitled to receive notice of, and to vote at, the annual meeting.

Important Notice Regarding Internet Availability of Proxy Materials for the Shareholder Meeting to be held on May 20, 2026.This notice of annual meeting, proxy statement, and our 2025 annual report to shareholders are being released to shareholders on or about April 1, 2026. This proxy statement and our 2025 annual report to shareholders are available on our website at www.oneok.com and www.proxydocs.com/oke.

Table of Contents

This proxy statement describes important issues affecting our company and is furnished in connection with the solicitation of proxies by our Board of Directors for use at our 2026 annual meeting of shareholders to be held at the time and place set forth in the accompanying notice.