Wulfsohn      POLYONE CORPORATION 67 Exhibit 31.1 CERTIFICATION I, Robert M. Richardson   POLYONE CORPORATION Exhibit 32.1 CERTIFICATION PURSUANT TO 18 U.S.C. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

In addition to our certification as an ACC Responsible Care® company, PolyOne has over 140 third-party certifications across multiple areas of expertise. Our third-party certifications span Quality, Environmental, Health & Safety, Automotive Quality, Laboratory Testing and Food Safety. These certifications are created and maintained via disciplined, sustainable processes that establish baseline expectations for our performance and remain evergreen.

Global Compact • Highlights ESG Performance, including ratings, awards, and certifications • Features increased carbon emissions disclosures, including Climate Change Scenario Analysis and Scope 3 emissions data • Outlines Sustainable Supplier Program, designed to enable supplier evaluation & collaboration • Reflects Great Place To Work® culture focused on safety, employee engagement and advancing diversity, equity and inclusion 2022 SUSTAINABILITY REPORT 15 Avient Confidential 16 • Virtual presentation to be held September 20, 2023 • Leadership will be conducting an investor-focused presentation around our sustainable solutions portfolio • Deep dive into how we enable customers to achieve their sustainability goals SUSTAINABILITY DAY 16 …are Growing at Twice the Rate as Conventional Products Sustainably-Branded Products… STAKEHOLDER INFLUENCE DRIVES DEMAND Consumers Are demanding recyclability and eco- conscious products Governments Are mandating changes through legislation, taxes, and regional accords Brand Owners Have committed to ambitious goals to achieve sustainability metrics 17 AP P EN D IX 20 Performance Additives 16% Pigments 12% TiO2 Dyestuffs 2% Polyethylene Nylon Polypropylene Styrenic Block Copolymer Other Raw Materials 33% ~40% hydrocarbon based (Grey shaded materials are hydrocarbon based, includes portion of “Other Raw Materials”) Non-hydrocarbon based materials 2022 pro forma results for the acquisition of Avient Protective Materials RAW MATERIAL BASKET PEER COMPARISONS AVIENT IS ASSET LIGHT Capex / Revenue 2023E (%) Avient Specialty Other Specialty / Note: Avient reflects 2023 estimated revenue of $3,280 and estimated run-rate CAPEX of $110M. 22 3 2 3 3 4 4 3 3 4 5 5 7 8 8 FREE CASH FLOW CONVERSION Note: Free cash flow conversion calculated as (Adjusted EBITDA – Capex) / Adjusted EBITDA.

When applying for a position, you may provide personal information, including: • Identifiers and Contact Information such as your name, date of birth, home address, personal email, phone number, government Identifiers (such as your driving license and/or national identification number); • Log In Details, including your email address, username and password when you sign in to submit your application; https://avient.referrals.selectminds.com/ https://www.avient.com/company/policies-and-governance/avient-corporation-privacy-statement mailto:HR@polyone.com • Protected Classifications, to the extent permitted by applicable law, such as your gender, race and ethnic origin; • Professional or Employment-Related Information, such as your resume or CV, employment background and history, job qualifications, the position for which you would like to submit an application, employment references, your current salary, bonuses, salary expectation or any other information you elect to provide, including information relating to any previous applications you may have submitted with us or any previous work experience with Avient, professional affiliations or memberships, and preferred start date; • Educational Information, such as educational background, your school transcripts, educational and training history, your English proficiency which may be required for certain positions, language and special competencies, certification information; and • Other personal information you choose to submit to us in connection with your application, such as contact information of references, information disclosed in an interview, or your personal situation In addition, as a part of the application process, you may be asked questions about your work authorization, and your willingness to submit to a background or criminal record check and/or medical examination as permitted by applicable law.

Exhibit 31.1 CERTIFICATION I, Robert M. Patterson Exhibit 31.2 CERTIFICATION I, Bradley C. Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).