Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the 2018 Equity Incentive Plan and the 2018 Employee Stock Purchase Plan of Principia Biopharma Inc. of our report dated March 19, 2019, with respect to the consolidated financial statements of Principia Biopharma Inc. included in its Annual Report (Form 10-K) for the year ended December 31, 2018, filed with the Securities and Exchange Commission.

/s/ Ernst & Young LLP

Redwood City, California

May 7, 2019