Exhibit 23

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statements (Form S-8, No. 333-212029 and No. 333-152928) of First Financial Northwest, Inc. of our report dated March 9, 2018, with respect to the consolidated financial statements and the effectiveness of internal control over financial reporting of First Financial Northwest, Inc. and Subsidiaries, appearing in this annual report on Form 10-K for the year endedDecember 31, 2017.

/s/ Moss Adams LLP

Everett, Washington

March 9, 2018