Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement (Form S-8 No. 333-226247) pertaining to the 2018 Equity Incentive Plan, the 2018 Employee Stock Purchase Plan and the 2012 Equity Incentive Plan of Allakos Inc. of our report dated March 14, 2019, with respect to the financial statements of Allakos Inc., included in this Annual Report (Form 10-K) for the year ended December 31, 2018.

/s/ Ernst & Young LLP

Redwood City, California

March 14, 2019