Certificate Number: CERT-0116814 Initial Certification Date: 24 November 2010 Date of Certification Decision: 25 March 2024 Issuing Date: 25 March 2024 Valid Until: 31 March 2027 Calin Moldovean President, Business Assurance Intertek Testing Services NA, Inc. dba Intertek, 4700 Broadmoor SE Suite 200 Kentwood, Michigan 49512, United States In the issuance of this certificate, Intertek assumes no liability to any party other than to the Client, and then only in accordance with the agreed upon Certification Agreement.

Inglis has taken on numerous special assignments in his tenure, including supporting Avient’s speciality transformation through M&A activity as well as establishing Avient’s Global Business Services (GBS).

You are advised to consult any further disclosures we make on related subjects in our reports on Form 10-Q, 8-K and 10-K that we provide to the Securities and Exchange Commission. The Company does not provide reconciliations of forward-looking non-GAAP financial measures, such as outlook for adjusted EBITDA, adjusted earnings per share, adjusted operating income and free cash flow, to the most comparable GAAP financial measures on a forward-looking basis because the Company is unable to provide a meaningful or accurate calculation or estimation of reconciling items and the information is not available without unreasonable effort. Leveraging Service as Our Timeless Differentiator — We serve our customers with excellence to build trusting, lasting and collaborative relationships.

Product/Service Overview Versaflex™ HC TPEs met regulatory needs and provided a recycled TPE solution for sealing ring

NYSE: AVNT) provides specialized and sustainable materials solutions that transform customer challenges into opportunities, bringing new products to life for a better world. Factors that could cause actual results to differ materially from those implied by these forward-looking statements include, but are not limited to: disruptions, uncertainty or volatility in the credit markets that could adversely impact the availability of credit already arranged and the availability and cost of credit in the future; the effect on foreign operations of currency fluctuations, tariffs and other political, economic and regulatory risks; disruptions or inefficiencies in our supply chain, logistics, or operations; changes in laws and regulations in jurisdictions where we conduct business, including with respect to plastics and climate change; fluctuations in raw material prices, quality and supply, and in energy prices and supply; demand for our products and services; production outages or material costs associated with scheduled or unscheduled maintenance programs; unanticipated developments that could occur with respect to contingencies such as litigation and environmental matters; our ability to pay regular quarterly cash dividends and the amounts and timing of any future dividends; information systems failures and cyberattacks; amounts for cash and non-cash charges related to restructuring plans that may differ from original estimates, including because of timing changes associated with the underlying actions; our ability to achieve strategic objectives and successfully integrate acquisitions, including the implementation of a cloud-based enterprise resource planning system, S/4HANA; other factors affecting our business beyond our control, including without limitation, changes in the general economy, changes in interest rates, changes in the rate of inflation, geopolitical conflicts, and any recessionary conditions; and other factors described in our Annual Report on Form 10-K for the year ended

Long fiber reinforced thermoplastics (LFTs) provide alternatives to and benefits over traditional materials used in aftermarket parts, offering designers fresh options with high strength, low density, resistance to moisture absorption, excellent design freedom, and the ability to eliminate secondary processing.  Product/Service Overview

Product/Service Overview Colorant Chromatics™ PTFE Dispersed Pigment Solutions improved manufacturing process and provided a range of custom color options

This is to certify that the Quality Management System of: Avient Corporation - HQ 33587 Walker Road The Quality Management System is applicable to: Certificate No: 31307 Certification Date: 12 October 1995 Effective Date: 20 September 2023 Expiration Date: 07 October 2025 Revision Date: 20 September 2023 Dominic Townsend, President MANUFACTURE AND SUPPLY OF PLASTIC COMPOUNDS, COLOR AND PERFORMANCE ADDITIVES, ENGINEERED THERMOPLASTICS, VINYL RESINS, CUSTOM MIXED PLASTIC MATERIALS, CUSTOM AND COMMODITY COLORANTS FOR PLASTICS, POLYURETHANE SYSTEMS, AND PLASTICIZERS WITH DESIGN AND SAMPLING SUPPORT AT SUWANEE, GA, AND PURCHASING, CUSTOMER SERVICE, LOGISTICS, QUALITY, DESIGN AND SAMPLING SUPPORT AT AVIENT CORPORATE HEADQUARTERS AT AVON LAKE, OH, AND DISTRIBUTION OF RESINS This certificate may be found on the ABS QE Website (www.abs-qe.com). Purchasing, Customer Service, Logistics, Quality, Design and Sampling; Corporate HQ, Management of QMS Activity: Manufacture of Engineered Thermoplastics Page 3 of 7 Facility: Avient Corporation - Massillon, OH 1675 Navarre Road Massillon, OH 44646 833 Ridgeview Drive Activity: Manufacture of Color and Performance Additives Activity: Design, Manufacture and Distribution of Thermoplastic Elastomer 831 Ridgeview Drive 921 Ridgeview Drive Activity: Design, Manufacture and Distribution of Thermoplastic Elastomer Activity: Design, Manufacture and Distribution of Thermoplastic Elastomer Facility: Avient Corporation - Lehigh Valley, PA 2513 Highland Avenue Bethlehem, PA 18017 Facility: Avient Corporation - Lockport, NY 4921 I D A Drive Lockport, NY 14094 Activity: Manufacture of Colorants for Plastics Activity: Manufacture of thermoplastic compounds Page 4 of 7 Facility: Avient Corporation- Suwanee, GA 2900 Shawnee Industrial Way Suwanee, GA 30024 Facility: Avient Corporation - Toluca, Mexico AV.

Leadership, EHS&S-PS, Facility Services, Design & Development, Information Technology, Sourcing, Logistics, Legal, and Human Resources 33587 Walker Road Avon Lake OH 44012 United States Avon Lake, OH (SEM) Design and Manufacture of Specialty Engineered Thermoplastics 554 Moore Road Avon Lake OH 44012 United States Kornkamp 50 Ahrensburg Schleswig- Holstein 22926 Germany Avient Corporation - Albany Design and Manufacture of Colorants and Additives for Plastics 4 Rothwell Ave, PO Box 300-009 Auckland 0632 New Zealand Avon Lake Color Design and Manufacture of Specialty Engineered Thermoplastics 33587 Walker Road, Building 416 Avon Lake OH 44012 United States Avient Corporation Design and Manufacture of Specialty Engineered Thermoplastics Pol. Water Street North Baltimore OH 45872 United States NEU Specialty Engineered Materials, LLC Compound, Supply, and Prototyping Services of Thermoplastics 15 Corporate Drive North Haven CT 06473 United States Avient Corporation Design and Manufacture of Colorants and Additives for Plastics 80 North West Street Norwalk OH 44857 United States Page 3 of 5 Avient Corporation Manufacture of Masterbatches, Additives, ECCOH, and Compounds for Pigmenting Thermoplastic Pol.

Certificate Avient Corporation S E s Certificate Of Conformance This is to certify that the Quality Management System of: Avient Corporation 33587 Walker Road, Building 428 Avon Lake OH 44012 United States has been assessed by ABS Quality Evaluations, Inc. and found to be in conformance with the requirements set forth by: ISO 9001:2015 The Quality Management System is applicable to: Manufacture of plastic compounds, color and performance additives, engineered thermoplastics, vinyl resins, custom mixed plastic materials, custom and commodity colorants for plastics, polyurethane systems, and plasticizers with design and sampling support at Suwanee, GA, and purchasing, customer service, logistics, quality, design and sampling support at PolyOne Corporate Headquarters at Avon Lake, OH, and distribution of resins Certificate No: 31307 Certification Date: 12 OCT 1995 Effective Date: 11 JUL 2024 Expiration Date 07 OCT 2025 Revision Date: 17 JUL 2024 Dominic Townsend, President Page 1 of 4 S E s ISO 9001:2015 Certificate Of Conformance ANNEX Certificate No.: 31307 Avient Corporation At the below facilities The Manufacture of Pultruded and Filament wound components Pultrusion and CRTM 3943, Valley East Industrial Drive, Buildings 1,2,3,4 Birmingham - AL 35217 United The Manufacture of Pultruded and Filament wound components Pultrusion and Filament Wound Tubing 3968, Valley East Industrial Drive, Building 5 Birmingham - AL 35217 United States The Manufacture of Pultruded and Filament wound components Pultrusion 3950, Valley East Industrial Drive, Building 6 Birmingham - AL 3517 United States Corporation Management of QMS. Purchasing, Customer Service, Logistics, Quality, Design and Sampling; Corporate HQ, Management of QMS 33587, Walker Road, Building 428 Avon Lake - OH 44012 United States Avon Lake, OH (SEM) Manufacture of Engineered Thermoplastics , 554 Moore Road Avon Lake - OH 44012 United States Aland (Odkarby), Finland Manufacture of colorants and compounds for fluoropolymer and high temperature polymers Kroklundsvagen 346 AX-22320 Ödkarby Finland Alicante (Ibi - IQAP), Spain Design, development and production of color concentrates and additives for plastic and synthetic fibers Guadalajara 6, Poligono Industrial L'Alfalç 03440 Ibi Assesse, Belgium (CAI & SEM) "Design of color concentrates, precolors, and compounds for fluoropolymer and high temperature polymers, LSFOH (low smoke and fume, zero halogen compounds), and Specialty Compounds Manufacture of Color and Additive Concentrates and Specialty Compounds" 2 Rue Melville Wilson 5330 Assesse Belgium Barbastro Design and Manufacture of Specialty Engineered Thermoplastics Pol.