Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

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

(1) Registration Statement (Form S-8 No. 333-191161) pertaining to the Onconova Therapeutics, Inc. 2013 Equity Compensation Plan

(2) Registration Statement (Form S-8 No. 333-194228) pertaining to the Onconova Therapeutics, Inc. 2013 Equity Compensation Plan

(3) Registration Statement (Form S-8 No. 333-204210) pertaining to the Onconova Therapeutics, Inc. 2013 Equity Compensation Plan

(4) Registration Statement (Form S-8 No. 333-210694) pertaining to the Onconova Therapeutics, Inc. 2013 Equity Compensation Plan

(5) Registration Statement (Form S-8 No. 333-215575) pertaining to the Onconova Therapeutics, Inc. 2013 Equity Compensation Plan

(6) Registration Statement (Form S-8 No. 333-222400) pertaining to the Onconova Therapeutics, Inc. 2013 Equity Compensation Plan

(7) Registration Statement (Form S-8 No. 333-226199) pertaining to the Onconova Therapeutics, Inc. 2018 Omnibus Incentive Compensation Plan

(8) Registration Statement (Form S-8 No. 333-233410) pertaining to the Onconova Therapeutics, Inc. 2018 Omnibus Incentive Compensation Plan

(9) Registration Statement (Form S-3 No. 333-237844) of Onconova Therapeutics, Inc.

(10) Registration Statement (Form S-3 No. 333-230744) of Onconova Therapeutics, Inc.

(11) Registration Statement (Form S-1 No. 333-211769) of Onconova Therapeutics, Inc.

(12) Registration Statement (Form S-1 No. 333-222374) of Onconova Therapeutics, Inc.

(13) Registration Statement (Form S-1 No. 333-224315) of Onconova Therapeutics, Inc.

(14) Registration Statement (Form S-1 No. 333-234360) of Onconova Therapeutics, Inc.

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

/s/ Ernst & Young LLP

Philadelphia, Pennsylvania

March 18, 2021