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. 333-231438) pertaining to the NextCure, Inc. 2019 Employee Stock Purchase Plan; and

(2) Registration Statement (Form S-8 No. 333-231436) pertaining to the NextCure, Inc. 2015 Omnibus Incentive Plan and the NextCure, Inc. 2019 Omnibus Incentive Plan;

of our report dated March 12, 2020, with respect to the financial statements of NextCure, Inc. included in this Annual Report (Form 10-K) of NextCure, Inc. for the year ended December 31, 2019.

/s/ Ernst & Young LLP

Baltimore, Maryland

March 12, 2020