Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the use in the Prospectus constituting a part of this Registration Statement on Amendment No. 1 to Form S-1 of our report dated September 9, 2025, relating to the financial statements of Bain Capital GSS Investment Corp., as of March 31, 2025 and for the period from March 24, 2025 (inception) through March 31, 2025, which is contained in that Prospectus. We also consent to the reference to our firm under the caption “Experts” in the Prospectus.

/s/ WithumSmith+Brown, PC

New York, New York

September 17, 2025