Custom Truck One Source, Inc.

Item 2.02. Results of Operations and Financial Condition. On August 3, 2026, Custom Truck One Source, Inc. (the "Company") issued a press release announcing its financial results for the quarter ended June 30, 2026. The press release is being furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference. The information in this Item 2.02, including Exhibit 99.1, shall be deemed "furnished" and not "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, and shall not be deemed to be incorporated by reference into any of the Company's filings under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, whether made before or after the date hereof and regardless of any general incorporation language in such filings, except to the extent expressly set forth by specific reference in such a filing.

Item 7.01. Regulation FD Disclosure. On August 3, 2026, the Company posted an updated investor presentation on its website at www.customtruck.com. The information in this Item 7.01 shall be deemed "furnished" and not "filed" for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, and shall not be deemed to be incorporated by reference into any of the Company's filings under the Securities Act or the Exchange Act, whether made before or after the date hereof and regardless of any general incorporation language in such filings, except to the extent expressly set forth by specific reference in such a filing.