POLYONE CORPORATION Exhibit 31.1 CERTIFICATION I, Stephen D. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C. ANNUAL CERTIFICATIONS PolyOne Corporation included as Exhibits 31.1 and 31.2 to its Annual Report on Form 10-K for 2012, filed with the Securities and Exchange Commission, certificates of its Chief Executive Officer and Chief Financial Officer certifying the quality of PolyOne’s public disclosure.

FX +4.6% FX -1.5% Total Avient +3.1% Note: Regional Sales Percentages exclude impact of foreign exchange Q2 2024 SEGMENT PERFORMANCE ( C O L O R , A D D I T I V E S & I N K S ) $525 $542 Q2 23 Q2 24 $94 $108 Q2 23 Q2 24 19.9% Sales Adjusted EBITDA (in millions) (in millions) Sales Adjusted EBITDA 10 17.9% +200 bps * * * Adjusted EBITDA Margin % • Organic sales growth in all regions led by Americas • Raw material deflation combined with cost reduction actions drove EBITDA margin expansion + 3% (+5% excluding FX) + 15% (+17% excluding FX) Q2 2024 SEGMENT PERFORMANCE ( S P E C I A LT Y E N G I N E E R E D M AT E R I A L S ) $301 $308 Q2 23 Q2 24 $60 $64 Q2 23 Q2 24 20.6% Sales Adjusted EBITDA (in millions) (in millions) Sales Adjusted EBITDA 11 19.8% +80 bps * * * Adjusted EBITDA Margin % • Sales growth in consumer, healthcare and building & construction end markets offset by weaker demand in telecommunications • EBITDA margin expansion driven by positive end market mix as well as raw material deflation + 2% (+4% excluding FX) + 7% (+8% excluding FX) 2 0 2 4 G U I D A N C E FY 20 24 GUIDA NC E Previous (May 7) Current Adjusted EBITDA $510 to $535 million $515 to $540 million Adjusted EPS $2.50 to $2.65 $2.55 to $2.70 Interest Expense $105 million $105 million Adjusted Effective Tax Rate 23% to 25% 23% to 25% Capital Expenditures ~$140 million ~$140 million 13 Q3 2024: Adjusted EPS of $0.62 14 Highlights • Provides performance updates on 2030 Sustainability Goals • Reduced company’s Scope 1 & 2 GHG emissions by 48% since 2019 • Highlights ESG performance ratings, certifications, and awards, including recent upgrades by Ecovadis to Gold and CDP to A- • Reflects Great Place to Work® culture focused on health, safety and employee engagement 20 23 SUSTAI NA BILI TY REPORT 14 Sustainability for a Better Tomorrow 2023 SUSTAINABILITY REPORT 15 • Investor Day to be held December 4, 2024 in New York, NY • The focus will be to do a deep dive on the Company’s strategy • Further details to be communicated 20 24 AVI ENT INVESTOR DAY A P P E N D I X 18 Performance Additives 15% Pigments 13% TiO2 9% Dyestuffs 2% Polyethylene 10%Nylon 5% Polypropylene 4% Styrenic Block Copolymer 4% Other Raw Materials 38% ~40% hydrocarbon based (Grey shaded materials are hydrocarbon based, includes portion of “Other Raw Materials”) Non-hydrocarbon based materials RA W MATERI AL BA SKET SEGMENT DATA U.S. & Canada 41% EMEA 36% Asia 18% Latin America 5% 2023 SEGMENT, END MARKET AND GEOGRAPHY GEOGRAPHY REVENUESEGMENT FINANCIALS Consumer 19% Packaging 23%Industrial 16% Building and Construction 9% Telecommunications 4% Energy 5% Defense 7% END MARKET REVENUE $2,007M $358M $1,138M $224M Sales EBITDA Specialty Engineered Materials Color Additives and Inks $502M$3,143M (1) Transportation 10% Healthcare 7% 20 (1) Total company sales and adjusted EBITDA of $3,143M and $502M, respectively, include intercompany sales eliminations and corporate costs 2 0 2 3 R E V E N U E | $ 2 . 0 B I L L I O N US & Canada 34% EMEA 37% Asia 21% Latin America 8% END MARKET REGION 21 Packaging 34% Consumer 21% Healthcare 8% Industrial 15% Transportation 9% Building & Construction 10% Telecommunications 1% Energy 2% COLOR , AD DI TI VES & INKS 2 0 2 3 R E V E N U E | $ 1 . 1 B I L L I O N US & Canada 52% EMEA 35% Asia 13% 22 Packaging 5% Consumer 16% Healthcare 6%Industrial 16% Transportation 12% Telecommunications 9% Energy 10% Defense 18% Building & Construction 8% END MARKET REGION SPEC IA LTY ENGI NEER ED MATERI ALS Packaging 32% Consumer 26% Healthcare 9% Industrial 13% Building & Construction 6% Telecommunications 2% Energy 2% Defense 1% Asia (18% of sales) Transportation 9% 2 0 2 3 AV I E N T R E G I O N A L S A L E S Packaging 25% Consumer 13% Healthcare 5% Industrial 18% Building & Construction 9% Energy 5% Defense 8% EMEA (36% of sales)Transportation 13% Packaging 13% Consumer 22% Healthcare 10% Industrial 16% Building & Construction 12% Energy 6% Defense 8% US & Canada (41% of sales) Transportation 9% Packaging 59% Consumer 22% Healthcare 2% Industrial 8% Building & Construction 4% LATAM (5% of sales) Transportation 5% Telecommunications 4% Telecommunications 4% 23 B Y E N D M A R K E T Reconciliation of Non-GAAP Financial Measures (Unaudited) (Dollars in millions, except for per share data) Senior management uses comparisons of adjusted net income from continuing operations attributable to Avient shareholders and diluted adjusted earnings per share (EPS) from continuing operations attributable to Avient shareholders, excluding special items, to assess performance and facilitate comparability of results.

We hold the American Chemistry Council's certification as a Responsible Care Management System® (RCMS) company. s/ Ernst & Young LLP Cleveland, Ohio February 22, 2022 Exhibit 31.1 CERTIFICATION I, Robert M. AVIENT CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

We hold the American Chemistry Council's certification as a Responsible Care Management System® (RCMS) company. Wulfsohn POLYONE CORPORATION 67 [THIS PAGE INTENTIONALLY LEFT BLANK] Exhibit 31.1 CERTIFICATION I, Robert M. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

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.

FX +4.6% FX -1.5% Total Avient +3.1% Note: Regional Sales Percentages exclude impact of foreign exchange Q2 2024 SEGMENT PERFORMANCE ( C O L O R , A D D I T I V E S & I N K S ) $525 $542 Q2 23 Q2 24 $94 $108 Q2 23 Q2 24 19.9% Sales Adjusted EBITDA (in millions) (in millions) Sales Adjusted EBITDA 7 17.9% +200 bps * * * Adjusted EBITDA Margin % • Organic sales growth in all regions led by Americas • Raw material deflation combined with cost reduction actions drove EBITDA margin expansion + 3% (+5% excluding FX) + 15% (+17% excluding FX) Q2 2024 SEGMENT PERFORMANCE ( S P E C I A LT Y E N G I N E E R E D M AT E R I A L S ) $301 $308 Q2 23 Q2 24 $60 $64 Q2 23 Q2 24 20.6% Sales Adjusted EBITDA (in millions) (in millions) Sales Adjusted EBITDA 8 19.8% +80 bps * * * Adjusted EBITDA Margin % • Sales growth in consumer, healthcare and building & construction end markets offset by weaker demand in telecommunications • EBITDA margin expansion driven by positive end market mix as well as raw material deflation + 2% (+4% excluding FX) + 7% (+8% excluding FX) 2 0 2 4 G U I D A N C E FY 20 24 GUIDA NC E Previous (May 7) Current Adjusted EBITDA $510 to $535 million $515 to $540 million Adjusted EPS $2.50 to $2.65 $2.55 to $2.70 Interest Expense $105 million $105 million Adjusted Effective Tax Rate 23% to 25% 23% to 25% Capital Expenditures ~$140 million ~$140 million 10 Q3 2024: Adjusted EPS of $0.62 11 Highlights • Provides performance updates on 2030 Sustainability Goals • Reduced company’s Scope 1 & 2 GHG emissions by 48% since 2019 • Highlights ESG performance ratings, certifications, and awards, including recent upgrades by Ecovadis to Gold and CDP to A- • Reflects Great Place to Work® culture focused on health, safety and employee engagement 20 23 SUSTAI NA BILI TY REPORT 11 Sustainability for a Better Tomorrow 2023 SUSTAINABILITY REPORT 12 • Investor Day to be held December 4, 2024 in New York, NY • The focus will be to do a deep dive on the Company’s strategy • Further details to be communicated 20 24 AVI ENT INVESTOR DAY A P P E N D I X 15 Performance Additives 15% Pigments 13% TiO2 9% Dyestuffs 2% Polyethylene 10%Nylon 5% Polypropylene 4% Styrenic Block Copolymer 4% Other Raw Materials 38% ~40% hydrocarbon based (Grey shaded materials are hydrocarbon based, includes portion of “Other Raw Materials”) Non-hydrocarbon based materials RA W MATERI AL BA SKET SEGMENT DATA U.S. & Canada 41% EMEA 36% Asia 18% Latin America 5% 2023 SEGMENT, END MARKET AND GEOGRAPHY GEOGRAPHY REVENUESEGMENT FINANCIALS Consumer 19% Packaging 23%Industrial 16% Building and Construction 9% Telecommunications 4% Energy 5% Defense 7% END MARKET REVENUE $2,007M $358M $1,138M $224M Sales EBITDA Specialty Engineered Materials Color Additives and Inks $502M$3,143M (1) Transportation 10% Healthcare 7% 17 (1) Total company sales and adjusted EBITDA of $3,143M and $502M, respectively, include intercompany sales eliminations and corporate costs 2 0 2 3 R E V E N U E | $ 2 . 0 B I L L I O N US & Canada 34% EMEA 37% Asia 21% Latin America 8% END MARKET REGION 18 Packaging 34% Consumer 21% Healthcare 8% Industrial 15% Transportation 9% Building & Construction 10% Telecommunications 1% Energy 2% COLOR , AD DI TI VES & INKS 2 0 2 3 R E V E N U E | $ 1 . 1 B I L L I O N US & Canada 52% EMEA 35% Asia 13% 19 Packaging 5% Consumer 16% Healthcare 6%Industrial 16% Transportation 12% Telecommunications 9% Energy 10% Defense 18% Building & Construction 8% END MARKET REGION SPEC IA LTY ENGI NEER ED MATERI ALS Packaging 32% Consumer 26% Healthcare 9% Industrial 13% Building & Construction 6% Telecommunications 2% Energy 2% Defense 1% Asia (18% of sales) Transportation 9% 2 0 2 3 AV I E N T R E G I O N A L S A L E S Packaging 25% Consumer 13% Healthcare 5% Industrial 18% Building & Construction 9% Energy 5% Defense 8% EMEA (36% of sales)Transportation 13% Packaging 13% Consumer 22% Healthcare 10% Industrial 16% Building & Construction 12% Energy 6% Defense 8% US & Canada (41% of sales) Transportation 9% Packaging 59% Consumer 22% Healthcare 2% Industrial 8% Building & Construction 4% LATAM (5% of sales) Transportation 5% Telecommunications 4% Telecommunications 4% 20 B Y E N D M A R K E T Reconciliation of Non-GAAP Financial Measures (Unaudited) (Dollars in millions, except for per share data) Senior management uses comparisons of adjusted net income from continuing operations attributable to Avient shareholders and diluted adjusted earnings per share (EPS) from continuing operations attributable to Avient shareholders, excluding special items, to assess performance and facilitate comparability of results.

Global Compact & fulfilled Communication of Progress (COP) requirements • New Sustainability Strategy overview page including our 2022 AIP ESG metrics • New ESG Performance page with ESG ratings, awards, and certifications • Increased disclosures on carbon emissions, including disclosure of Climate Change Scenario Analysis • Added new Product Stewardship and Chemical Management policies • Enhanced data reporting for Workforce Demographics • Improved social disclosures on human rights, dependent care and special leave and strategic training management 20 21 SUSTAI NA BILI TY REPORT Launching integrated sustainability website in parallel with report Aligned with leading reporting frameworks 6 Released July 2022 E S G R AT I N G S P E R F O R M AN C E E S G AWA R D S AN D C E R T I F I C AT I O N S ESG PER FORMANCE & A WAR DS 84th 3 1 2 7 T R A N S F O R M A T I O N A L O V E R V I E W Avient Protective Materials Dyneema ® RECENT TRANSAC TIONS Acquired Divested $1.45 B $0.95 B 9 Distribution UPDATED CA PI TAL STRUC TURE & LI QUI DI TY • Proceeds from completed sale of Distribution used to pay near-term maturing debt to strengthen balance sheet • Fixed/floating debt ratio of ~55/45 • Proven track record of deleveraging following major acquisitions through strong free cash flow generation • 2022 pro forma net debt/adjusted EBITDA expected to be 3.1x $725 $725 $575 $500 $600 $525 $650 $650 $600 Capital Structure Cas h $544 Undr awn Rev olve r $250 Liquidity $3.15B $2.40B 2030 Notes 2029 Term Loan 2026 Term Loan 2025 Notes 2023 Notes After Dyneema Acquisition After Distribution Divestiture $794M (1) (1) $250M reflects estimated undrawn revolver following the divestiture of Distribution 10 PREVI OUS TR ANSACTIONS Performance Solutions Products & $0.8 B COLOR $1.4 B Acquired (2020)Divested (2019) 11 • Acquisition of Clariant Color business significantly expanded presence in healthcare, packaging and consumer end markets • Strength of portfolio – double-digit annual EBITDA growth since acquisition • $75 million of realized synergies anticipated in 2022 • Acquisition completed on July 1, 2020 for $1.45 billion.

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 20 22 SUSTAI NA BILI TY 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… STAKEHOLD ER INFLUENC E D RI VES D EMA ND 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 A P P E N D I X 20 Performance Additives 16% Pigments 12% TiO2 10% Dyestuffs 2% Polyethylene 11% Nylon 6% Polypropylene 5% Styrenic Block Copolymer 5% 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 RA W MATERI AL BA SKET PEER COMPARISONS AVI ENT I S ASSET LI GHT Capex / Revenue 2023E (%) Avient Specialty Formulators Other Specialty / Chemical Companies Source: Peer data per Bloomberg as of July 21, 2023 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 A vi e n t K W R P P G F U L R P M A V Y F M C H U N C E H X L E C L A S H E M N S C L FR EE CA SH FLOW CONV ER SION Source: Peer data per Bloomberg as of July 21, 2023 Note: Free cash flow conversion calculated as (Adjusted EBITDA – Capex) / Adjusted EBITDA.

Global Compact & fulfilled Communication of Progress (COP) requirements • New Sustainability Strategy overview page including our 2022 AIP ESG metrics • New ESG Performance page with ESG ratings, awards, and certifications • Increased disclosures on carbon emissions, including disclosure of Climate Change Scenario Analysis • Added new Product Stewardship and Chemical Management policies • Enhanced data reporting for Workforce Demographics • Improved social disclosures on human rights, dependent care and special leave and strategic training management 20 21 SUSTAI NA BILI TY REPORT Launching integrated sustainability website in parallel with report Aligned with leading reporting frameworks 6 Released July 2022 E S G R AT I N G S P E R F O R M AN C E E S G AWA R D S AN D C E R T I F I C AT I O N S ESG PER FORMANCE & A WAR DS 84th 3 1 2 7 T R A N S F O R M A T I O N A L O V E R V I E W Avient Protective Materials Dyneema ® RECENT TRANSAC TIONS Acquired Divested $1.45 B $0.95 B 9 Distribution UPDATED CA PI TAL STRUC TURE & LI QUI DI TY • Proceeds from completed sale of Distribution used to pay near-term maturing debt to strengthen balance sheet • Fixed/floating debt ratio of ~55/45 • Proven track record of deleveraging following major acquisitions through strong free cash flow generation • 2022 pro forma net debt/adjusted EBITDA expected to be 3.1x $725 $725 $575 $500 $600 $525 $650 $650 $600 Capital Structure Cash $544 Undrawn Revolver $250 Liquidity $3.15B $2.40B 2030 Notes 2029 Term Loan 2026 Term Loan 2025 Notes 2023 Notes After Dyneema Acquisition After Distribution Divestiture $794M (1) (1) $250M reflects estimated undrawn revolver following the divestiture of Distribution 10 PREVI OUS TR ANSACTIONS Performance Solutions Products & $0.8 B COLOR $1.4 B Acquired (2020)Divested (2019) 11 • Acquisition of Clariant Color business significantly expanded presence in healthcare, packaging and consumer end markets • Strength of portfolio – double-digit annual EBITDA growth since acquisition • $75 million of realized synergies anticipated in 2022 • Acquisition completed on July 1, 2020 for $1.45 billion.

POLYONE CORPORATION [THIS PAGE INTENTIONALLY LEFT BLANK] Exhibit 31.1 CERTIFICATION I, Robert M. Patterson Chairman, President and Chief Executive Officer February 16, 2017 POLYONE CORPORATION Exhibit 31.2 CERTIFICATION I, Bradley C. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.