Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the reference to our firm under the caption “Experts” and to the use of our report dated May 24, 2021, in the Registration Statement (Form S-1) and related Prospectus of Xilio Therapeutics, Inc. dated October 1, 2021 for the registration of shares of its common stock.

/s/ Ernst & Young LLP

Boston, Massachusetts

October 1, 2021