Exhibit 5.1

Seattle, WA 98104-7036

PHONE 206.883.2500

FAX 206.883.2699

www.wsgr.com

February 28, 2019

Impinj, Inc.

400 Fairview Avenue North, Suite 1200

Seattle, Washington 98109

Re: Registration Statement on Form S-8 

Ladies and Gentlemen:

We have examined the Registration Statement on Form S-8 (the “Registration Statement”) to be filed by Impinj, Inc., a Delaware corporation, with the Securities and Exchange Commission on or about the date hereof, in connection with the registration under the Securities Act of 1933, as amended, of an aggregate of 1,292,406 shares of your common stock, par value $0.001 per share (the “Shares”), consisting of: (1) 1,077,005 shares of common stock to be issued under the 2016 Equity Incentive Plan (the “2016 Plan”) and (2) 215,401 shares of common stock to be issued under the 2016 Employee Stock Purchase Plan (the “2016 ESPP,” and together with the 2016 Plan, the “Plans”). As your legal counsel, we have reviewed the actions proposed to be taken by you in connection with the issuance and sale of the Shares to be issued under the Plans.

It is our opinion that the Shares, when issued and sold in the manner referred to in the Plans and pursuant to the agreements that accompany the Plans, will be legally and validly issued, fully paid and nonassessable.

We consent to the use of this opinion as an exhibit to the Registration Statement, and further consent to the use of our name wherever appearing in the Registration Statement and any amendments thereto.

Sincerely,

/s/ Wilson Sonsini Goodrich & Rosati, P.C.

WILSON SONSINI GOODRICH & ROSATI

Professional Corporation

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