Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. Effective October 16, 2025, the Board of Directors (the “ Board”) of Solaris Energy Infrastructure, Inc. (the “ Company”) (i) appointed Ms. Amanda M. Brock as Co-ChiefExecutive Officer of the Company and (ii) appointed Ms. Brock to the Board to fill the vacancy created by the previously reported passing of Mr. F. Gardner Parker on April 26, 2025. Ms. Brock will serve as a Class I director, with a term expiring at the 2027 annual meeting of stockholders, and until she is either reelected or her successor is elected and qualified, or until her earlier death, resignation or removal, to fill the newly created vacancy. Ms. Brock will serve, along Mr. William A. Zartler, as co-principalexecutive officer of the Company. Prior to joining the Company, Ms. Brock, age 64, served as President and Chief Executive Officer of Aris Water Solutions, Inc. (NYSE: ARIS) (“ Aris Inc.”) from September 2021 until October 2025. Ms. Brock joined Solaris Midstream Holdings, LLC, Aris’s predecessor (“ Aris LLC” and, together with Aris Inc., “ Aris”), in 2017 as the Senior Commercial Advisor and assumed the President and Chief Operating Officer positions in September 2020 and July 2018, respectively. Ms. Brock also served as Chief Commercial Officer of Aris from February 2018 to September 2020. Ms. Brock also served as a Director of Aris from December 2020 until October 2025. Ms. Brock has spent her career focused on the global water, power and energy sectors. Before joining Aris, Ms. Brock was Chief Executive Officer of Water Standard, a water treatment company focused on desalination and produced water treatment and recycling in both the upstream and downstream energy industries, from 2009 to 2017. Previously, Ms. Brock was President of the Americas for Azurix and was responsible for developing water infrastructure and services in the Americas. Ms. Brock has served on the board of Coterra Energy Inc. (NYSE: CTRA) (formerly Cabot Oil & Gas Corporation) since 2017. Ms. Brock served on the board of Macquarie Infrastructure Holdings, LLC (NYSE: MIC) (formerly Macquarie Infrastructure Corporation) from August 2018 until June 2022. Ms. Brock is also on the Executive Committee and is the chair of the Texas Business Hall of Fame. She previously served on the Board of Trustees of LSU Law School and the Texas Water Commission. She completed her undergraduate degree in South Africa and earned her law degree at Louisiana State University, where she was a member of the Law Review, and began her career as a lawyer at Vinson & Elkins LLP. Ms. Brock was previously named one of the Top 10 Women in Energy by the Houston Chronicle and in 2016, one of the Top 25 in water globally by Water and Wastewater International. In 2020, Ms. Brock was named one of the Top 25 Influential Women in Energy by Hart Magazine. There are no family relationships between Ms. Brock and any director or executive officer of the Company or any person nominated or chosen by the Company to become a director or executive officer. There are no arrangements or understandings between Ms. Brock and any other person pursuant to which Ms. Brock was appointed as the Company’s Co-ChiefExecutive Officer or elected as a director. The Company is not aware of any transaction involving Ms. Brock that would require disclosure under Item 404(a) ofRegulation S-Kpromulgated under the Securities Exchange Act of 1934, as amended (the “ Exchange Act”).

Item 7.01 Regulation FD Disclosure. On October 15, 2025, the Company issued a press release announcing Ms. Brock’s appointment as Co-ChiefExecutive Officer of the Company and to the Board as a new director, effective October 16, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form8-Kand is incorporated into this Item 7.01 by reference. In accordance with General Instruction B.2 of Form 8-K, theinformation contained in this Current Report on Form 8-K underthis Item 7.01 and set forth in the attached Exhibit 99.1 shall not be deemed to be “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor shall such information be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific referencing in such filing.

Item 9.01 Financial Statements and Exhibits. (d) Exhibits Exhibit Description No. ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 10.1 Form of Solaris Oilfield Infrastructure, Inc. Executive Change in Control Severance Plan, effective as of March 1, 2023 (incorporated by reference to Exhibit 10.1 to the Registrant’s Form 8-K (File No. 001-38090) filed with the Commission on March 7, 2023). 10.2 Indemnification Agreement (Amanda M. Brock). 99.1 Press Release, dated October 15, 2025. 104 Cover Page Interactive Data File (embedded within Inline XBRL document). SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Date: October 17, 2025 SOLARIS ENERGY INFRASTRUCTURE, INC. By: /s/ Kyle S. Ramachandran Name: Kyle S. Ramachandran Title: President and Chief Financial Officer