Exhibit 23.1

Consentof Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the following Registration Statements:

(1)Registration Statement (Form S-8 No. 333-201816) pertaining to the 2014 Equity Incentive Plan, 2015 Equity Incentive Plan and 2015 Employee Stock Purchase Plan of Salarius Pharmaceuticals, Inc. (formerly known as Flex Pharma, Inc.);

(2)Registration Statement (Form S-8 Nos. 333-210283, 333-216534, 333-223499, 333-230104 and 333-246310) pertaining to the 2015 Equity Incentive Plan and 2015 Employee Stock Purchase Plan of Salarius Pharmaceuticals, Inc. (formerly known as Flex Pharma, Inc.);

(3)Registration Statement (Form S-3 No. 333-231010 and 333-252169) of Salarius Pharmaceuticals, Inc. (formerly known as Flex Pharma, Inc.);

(4)Registration Statement (Form S-1 No. 333-235879) of Salarius Pharmaceuticals, Inc.

of our report dated March 18, 2021, with respect to the consolidated financial statements of Salarius Pharmaceuticals, Inc. included in this Annual Report (Form 10-K) of Salarius Pharmaceuticals, Inc. for the year ended December 31, 2020.

/s/ Ernst & Young LLP

Houston, Texas

March 18, 2021