About PolyOne To access PolyOne’s news library online, please go to www.avient.com/news. PolyOne Corporation

273138-2018-AQ-RGC-IATF IATF Certificate No: 0558323 Valid: 10 December 2024 – 09 December 2027 This is to certify that the management system of Polyone - Shenzhen Co., Ltd. ACCREDITED UNIT: DNV Business Assurance USA Inc., 1400 Ravello Drive, Katy, TX, 77449-5164, USA - TEL: +1 281-396-1000. www.dnv.com Page 2 of 2 Appendix to Certificate Polyone - Shenzhen Co., Ltd. China 201206 (USI: PKFHC3) Process Design, Product Design DNV PolyOne-Suzhou, China 77 Shenggang Street SIP, Suzhou, Jiangsu, China 215127 (USI: CF4943) Contract Review, Sales, Supplier Management DNV http://www.dnv.com

Homepage // News Center // PolyOne Highlights Advanced Healthcare Solutions at Medtec Europe 2014

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In 2016, Avient - which, at the time, was operating as PolyOne - announced development of a lightweight, carbon fiber-reinforced underbody brace, which is offered as a performance upgrade for the C7 generation of General Motors’ popular Chevrolet Corvette sports car.                                              Image ©PolyOne Caption: Advanced composite underbody braces from PolyOne are available as a performance upgrade for all C7 Corvettes.

Avient was formed as PolyOne Corporation on August 31, 2000 from the consolidation of The Geon Company (Geon) and M.A. Under the agreement, The Geon Company agreed to indemnify Goodrich Corporation for certain environmental costs at the site. Wulfsohn 73 AVIENT CORPORATION 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. 333-238246) pertaining to the PolyOne Corporation 2020 Equity and Incentive Compensation Plan; (2) Registration Statement (Form S-8 No. 333-231236) pertaining to the PolyOne Supplemental Retirement Benefit Plan (As Amended and Restated Effective January 1, 2014); (3) Registration Statement (Form S-8 No. 333-217879) pertaining to the PolyOne Corporation 2017 Equity and Incentive Compensation Plan; (4) Registration Statement (Form S-8 No. 333-205919) pertaining to the Amended and Restated PolyOne Corporation 2010 Equity and Performance Incentive Plan; (5) Registration Statement (Form S-8 No. 333-181787) pertaining to the PolyOne Corporation 2010 Equity and Performance Incentive Plan; (6) Registration Statement (Form S-8 No. 333-166775) pertaining to the PolyOne Corporation 2010 Equity and Performance Incentive Plan; (7) Registration Statement (Form S-8 No. 333-157486) pertaining to the PolyOne Retirement Savings Plan; (8) Registration Statement (Form S-8 No. 333-47796) pertaining to Post-Effective Amendment No. 3 on Form S-8 to Form S-4 pertaining to the Geon Company 1993 Incentive Stock Plan, the Geon Company 1995 Incentive Stock Plan, the Geon Company 1998 Interim Stock Award Plan, the Geon Company 1999 Incentive Stock Plan, the PolyOne Corporation Deferred Compensation Plan for Non-Employee Directors and the M.A.

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PHTHALATES IN PLASTICS KNOWING THE FACTS Phthalates are a group of chemicals used to make plastics, and in particular polyvinyl chloride (PVC), more flexible. They are used in a remarkably wide variety of flexible PVC products found in our homes and businesses.

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LoC No: 798019/2023 Page 1 of 1 Letter of Conformity Good Manufacturing Practices — Guidelines The Letter of Conformity is granted to Polyone Polymers India Private Limited Plot No.