Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statements on FormS-8 (Nos.333-236229, 333-232106, 333-226701, and 333-218468) and Form S-3 (No. 333-225678) of G1 Therapeutics, Inc. of our report dated February 26, 2020 relating to the financial statementsand the effectiveness of internal control over financial reporting, which appears in this Form 10-K.

/s/ PricewaterhouseCoopers LLP
Raleigh, North CarolinaFebruary 26, 2020