Hyliion Holdings Corp.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

Check the appropriate box:

Hyliion Holdings Corp.

(Name of Registrant as Specified in Its Charter)

Payment of Filing Fee (Check the appropriate box):

1202 BMC Drive

Cedar Park, Texas 78613

Dear Fellow Stockholders:

You are cordially invited to attend the Annual Meeting of Stockholders of Hyliion Holdings Corp. on Tuesday, May 19, 2026 at 12:00 p.m. Central Time. We are pleased to utilize a virtual format for our Annual Meeting again this year. You will be able to attend the Annual Meeting, submit your questions and vote online during the meeting by visiting https://www.cstproxy.com/hyliion/2026. Our Annual Meeting will only be accessible online as discussed in greater detail in the Proxy Statement. We believe a virtual meeting provides expanded access, improves communication, enables increased stockholder attendance and participation and provides cost savings for our stockholders and the Company.

As described in the accompanying Notice and Proxy Statement, at the Annual Meeting you will be asked to (1) elect the three directors named in the Proxy Statement to serve until the 2029 Annual Meeting of Stockholders or until their respective successors are elected and qualified; (2) ratify the appointment of Grant Thornton LLP as our independent auditors for the fiscal year ended December 31, 2026; (3) approve, on an advisory basis, our named executive officers’ compensation; and (4) approve an amendment to the Hyliion Holdings Corp. 2024 Equity Incentive Plan to increase the aggregate number of shares of common stock available for issuance thereunder.

We look forward to you joining us at the virtual Annual Meeting. Thank you for your continued support.

Sincerely,

Jeffrey Craig Thomas Healy

Board Chair Founder & CEO, Director

NOTICE OF 2026 ANNUAL MEETING OF STOCKHOLDERS AND PROXY STATEMENT

12:00 p.m. Central Time

Tuesday, May 19, 2026

Virtual Meeting Site: https://www.cstproxy.com/hyliion/2026

Dear Stockholder:

Notice is hereby given that the 2026 Annual Meeting of Stockholders (“Annual Meeting”) of Hyliion Holdings Corp., a Delaware corporation (the “Company”) will be held on Tuesday, May 19, 2026 at 12:00 p.m. Central Time athttps://www.cstproxy.com/hyliion/2026. Our Annual Meeting will only be accessible online as discussed in greater detail in the Proxy Statement.

The Board of Directors has fixed March 25, 2026 as the record date for determining stockholders entitled to receive notice of, and to vote at, the Annual Meeting or adjournment or postponement thereof. Only stockholders of record at the close of business on that date will be entitled to notice of, and to vote at, the Annual Meeting. Our proxy materials are first being made available to our stockholders beginning on April 2, 2026.

By Order of the Board of Directors,

Jose Oxholm

Chief Legal and Compliance Officer

Important Notice Regarding the Availability of Proxy Materials for the Hyliion 2026 Annual

Meeting to be Held on May 19, 2026.

This Notice, Proxy Statement and our 2025 Annual Report are available at

https://www.cstproxy.com/hyliion/2026

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Proxy Statement and documents referenced herein contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), including, but not limited to, statements that are based upon management’s current expectations, assumptions, estimates, projections and beliefs, including statements about the commercial progress and future financial performance of the Company. The use of words such as, but not limited to, “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will,” or “would” and similar words or expressions are intended to identify forward-looking statements. These statements involve risks, uncertainties and other factors that may cause actual results or achievements to be materially different and adverse from those expressed in or implied by these forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements. New risks and uncertainties may emerge from time to time, and it is not possible to predict all risks and uncertainties. Other risks relating to the Company’s business, including risks that could cause results to differ materially from those projected in the forward-looking statements in this Proxy Statement, are detailed in the Company’s latest Form 10-K, subsequent Forms 10-Q and/or Form 8-K filings with the U.S. Securities and Exchange Commission (the “SEC”), especially under the heading “Risk Factors.” The forward-looking statements in this Proxy Statement and documents referenced herein speak only as of this date, and the Company disclaims any intent or obligation to revise or update publicly any forward-looking statement except as required by law.