We hold the American Chemistry Council's certification as a Responsible Care Management System® (RCMS) company. s/ Ernst & Young LLP Cleveland, Ohio February 22, 2023 Exhibit 31.1 CERTIFICATION I, Robert M. AVIENT CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

Further, we recently achieved the American Chemistry Council's certification as a Responsible Care Management System® (RCMS) company. Wulfsohn POLYONE CORPORATION68 Exhibit 31.1 CERTIFICATION I, Robert M. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

For our sensitive applications, we have implemented ISO 13485 and Good Manufacturing Processes (GMP). 100% of our facilities producing those sensitive applications and warehouses are GMP audited within a 3–year period. 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.

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product con- forms at the time of shipment to a Certificate of Analysis, a Cer- tificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”). Säljaren garanterar att de produkter som är föremål för försäljningen (”Produkten”) är fria från rättsliga fel och att Produkten vid leveranstidpunkten stämmer överens med ett så kallat ”Certificate of Analysis”, ett ”Certificate of Compliance” eller ett ”Product Specification Sheet”, om något sådant existerar, och med andra specifikationer undertecknade av Säljaren (”Specifikationer”).

Stringers Bulkheads, Decking and Transoms Doors and Cabinetry Ceilings and Hatches MECHANICAL PERFORMANCE Superior strength-to-weight ratio PROPERTY TEST METHOD PANEL THICKNESS .50" .75" 1.00" 1.50" Core Density (lb/ft3) ISO 845 5.3 8.4 5.3 8.4 5.3 8.4 5.3 8.4 Flexural Rigidity (lb-in2) ASTM D7249 38,379 39,390 80,699 74,158 147,890 140,081 342,866 363,009 Panel Weight (lb/ft2) Calculated 0.93 1.07 1.03 1.25 1.14 1.42 1.35 1.77 Core Shear Yield (psi) ASTM C393 60 138 61 139 57 131 52 99 Max Load (lbs) ASTM C393 246 482 362 704 423 833 558 1,031 Core Shear ULT (psi) ASTM C393 81 159 81 153 70 138 62 113 Face Bend Stress (psi) ASTM C393 6,430 12,582 6,355 12,109 5,511 10,860 4,899 8,916 USES & APPLICATIONS SUPPORT SPAN DEFLECTION Meets performance required for marine applications Predictive deflection in various load cases.

FEATURED TPES FOR CONSUMER APPLICATIONS CO N SU M ER GENERAL PROPERTIES REGULATORY OVERMOLDING PROCESS FEATURES Appearance Hardness Specific Gravity Food Contact UL 94 Suitable Substrates Injection Extrusion ASTM Shore ASTM (D792) Consumer Electronics Series Versaflex™ CE 3120-40 Natural 42A 0.92 - - PC, ABS, PC/ABS, COPE ✔ - Good compression set—ideal for device cases or electronic grips Versaflex™ CE 3120-65 Natural 66A 1.15 - HB PC, ABS, PC/ABS, COPE ✔ - Chemical and abrasion resistant; 4.69 cradle-to-gate PCF—ideal for device cases or electronic grips Versaflex™ CE 3140-65N Natural 65A 1.00 - - PC, ABS, PC/ABS, COPE ✔ - 5G transparent materials—ideal for device cases or gaskets Versaflex™ CE 3140-90N Natural 90A 1.01 - - PC, ABS, PC/ABS, COPE ✔ - 5G transparent materials—ideal for device cases or gaskets Versaflex™ CE 3620 Black/ Natural 65A 1.00 - HB PC, ABS, PC/ABS, COPE ✔ - Chemical and abrasion resistant, hydrolitically stable—ideal for electronic grips/gaskets or wearables Engineering Resin Overmolds Versaflex™ OM 1060X-1 Natural 60A 0.93 ✔ - PC, ABS, PC/ABS ✔ - Versatile OM resin—ideal for grips/gaskets Versaflex™ OM 9-801N Natural 47A 1.04 ✔ HB PC, ABS, PC/ABS, PPO, POM, COPE, PMMA, HIPS ✔ - Soft touch/rubber feel—ideal for grips/gaskets Versaflex™ OM 9-802CL Clear 40A 0.92 ✔ - PC, ABS, PC/ABS, COPE ✔ - Soft touch/rubber feel—ideal for grips/gaskets Versaflex™ OM 6059-9 Black 58A 1.10 - HB PA 6 and 6,6 ✔ - Superior adhesion—ideal for grips, power tools/equipment Versaflex™ OM 6160-1 Black/ Natural 60A 1.11 ✔ HB PA 6 and 6,6 ✔ Superior adhesion—ideal for grips, power tools/equipment Versaflex™ OM 6240-1 Natural 43A 1.09 - - PA 6 and 6,6 ✔ - Superior adhesion — ideal for grips, power tools/equipment Versaflex™ OM 6258-1 Natural 62A 1.09 - - PA 6 and 6,6 ✔ - Superior adhesion—ideal for grips, power tools/equipment Versaflex™ OM 6258-9 Black 62A 1.09 - HB PA 6 and 6,6 ✔ - Superior adhesion—ideal for grips, power tools/equipment Versaflex™ OM 6275-9 Black 75A 1.10 - - PA 6 and 6,6 ✔ - Superior adhesion—ideal for grips, power tools/equipment Versollan™ OM1255NX Black 59A 1.05 - HB PC, ABS, PC/ABS, PC/PBT, COPE ✔ - Superior adhesion—ideal for power tool grips Versollan™ RU 2205-1 Natural 65A 1.16 - HB PC, ABS, PC/ABS, COPE ✔ ✔ High performance, rubber feel GENERAL PROPERTIES REGULATORY OVERMOLDING PROCESS FEATURES Appearance Hardness Specific Gravity Food Contact UL 94 Suitable Substrates Injection Extrusion ASTM Shore ASTM (D792) Special Series Versaflex™ VDT 4202-40B Black 40A 1.00 - - PP ✔ ✔ Vibration dispersion—ideal for washer/dryer feet or shin guards Versaflex™ G2800-17 Pink 18 OO 0.85 - - - ✔ - Skin-like feel—ideal for adult toys Versaflex™ SP 2820-55N Natural 55A 0.91 ✔ - - ✔ ✔ Superior puncture and tear resistance—ideal for dog toys Versaflex™ XP 2850 Natural 55A 0.88 ✔ - - ✔ ✔ Wet grip—ideal for water sports or grips Versaflex™ GP 2810-40N AM US Translucent 45A 0.87 ✔ - - ✔ - Antimicrobial Versaflex™ CE 3120-65 AM Natural 67A 1.15 - - PC, ABS, PC/ABS, COPE ✔ - Antimicrobial for consumer electronics Versalloy™ XL 9045-1 Natural 44A 0.88 ✔ - - ✔ - Excellent flow for long, thin flow paths— ideal for grips or thin wall parts Versalloy™ XL 9055-1 Natural 53A 0.89 ✔ - PP ✔ - Excellent flow for long, thin flow paths— ideal for grips or thin wall parts Versalloy™ XL 9055X-9 Black 53A 0.89 ✔ HB PP ✔ - Excellent flow for long, thin flow paths— ideal for grips or thin wall parts Versalloy™ XL 9070-1 Natural 70A 0.89 ✔ - PP ✔ - Excellent flow for long, thin flow paths— ideal for grips or thin wall parts Versalloy™ XL 9070X-9 Black 70A 0.89 ✔ HB PP ✔ - Excellent flow for long, thin flow paths; 2.54 cradle-to-gate PCF—ideal for grips or thin wall parts Dynaflex™ G7702-9001-02 Black 37A 1.10 - - PP ✔ ✔ High temperature performance—ideal for seals and gaskets Dynalloy™ DT 7910W White 45A 0.93 ✔ - - ✔ ✔ Low compression—ideal for dairy tubing Versaflex™ CL 2000X Clear 3A 0.87 ✔ - - ✔ ✔ Ultra soft Versaflex™ CL 2003X Clear 33 OO 0.87 ✔ - - ✔ ✔ Gel feel Versaflex™ CL30 Clear 30A 0.89 ✔ - PP ✔ ✔ High clarity, high tackiness Versaflex™ CL40 Clear 43A 0.89 ✔ HB - ✔ ✔ High clarity, high tackiness General Purpose Series Versaflex™ GP 2810 Translucent 20A–60A 0.88 ✔ - - ✔ ✔ Unfilled Versaflex™ GP 2810 Translucent 70A–90A 0.89 ✔ HB - ✔ ✔ Unfilled Dynaflex™ G7920 Natural/Black 20A 1.01 ✔ - PP ✔ ✔ Filled Dynaflex™ G7900 Natural/Black 30A–90A 1.05–1.20 ✔ HB PP ✔ ✔ Filled FEATURED TPES FOR CONSUMER APPLICATIONS CO N SU M ER GENERAL PROPERTIES REGULATORY OVERMOLDING PROCESS FEATURES Appearance Hardness Specific Gravity Compression Set @ 23°C Compression Set @ 100°C Food Contact ISO 10993 USP VI UL 94 Suitable Substrates Injection Extrusion ASTM Shore A ASTM (D792) ASTM % ASTM % Tubing Versaflex™ G2705 N Translucent 60 0.89 20 - ✔ ✔ ✔ ✔ PP ✔ ✔ High resiliance, low compression set, and good puncture sealing–ideal for medical and biopharma tubing Versaflex™ HC BT218 Translucent 67 0.89 19 69 - ✔ ✔ ✔ - - ✔ Weldable and kink resistant—ideal for biopharma tubing Versalfex™ HC BIO BT218 Translucent 70 0.88 18 58 - ✔ ✔ - - - ✔ Weldable and kink resistant; 40% bio-derived content (Gen 1 biomass)—ideal for biopharma tubing Versaflex™ HC MT317 Translucent 68 0.89 17 69 - ✔ ✔ ✔ - - ✔ Flexible and kink resistant, high service temperature —ideal for medical and biopharma tubing Versalloy™ HC 9220-70 Natural 70 0.95 17 51 - ✔ ✔ - PP ✔ ✔ High temperature resistance—ideal for peristaltic pump tubing Syringe Components Versaflex™ HC 2110-35N Natural 35 0.89 19 47 - ✔ ✔ - LDPE, PP ✔ - Good puncture sealing and elevated temperature performance—ideal for septums Versaflex™ HC 2110-57B Black 57 1.01 20 37 - ✔ ✔ - - ✔ - Low coefficient of friction and elevated temperature performance—ideal for plungers and stoppers Engineering Resin Overmolds Versaflex™ OM 1040X-1 Translucent 42 0.92 22 - ✔ ✔ ✔ - PC, ABS, PC/ABS ✔ - Good compression set at room temperature— ideal for seals and grips Versaflex™ OM 3060-1 Clear 59 0.90 33 - ✔ ✔ ✔ HB PC, ABS, PC/ABS, PC/PETG, PC/PBT ✔ - Good compression set at room temperature and UV stability—ideal for seals and grips Versaflex™ OM 8940X-1 Clear 40 0.92 20 - ✔ ✔ - - PK, COPE, PC, ABS, PC/ABS ✔ - Excellent chemical resistance to alcohols and disenfectants—ideal for grips on medical devices Versaflex™ OM 4052 Translucent 56 1.01 27 - ✔ - - - PC, ABS, PC/ABS ✔ - Excellent chemical resistance to skin oils, like sebum, and hand lotion—ideal for consumer healthcare applications Versaflex™ OM 4063 Translucent 64 1.12 30 - ✔ - - PC, ABS, PC/ABS ✔ - Excellent chemical resistance to skin oils, like sebum, and hand lotion—ideal for consumer healthcare applications General Purpose Applications Versaflex™ CL E85 Clear 85 0.90 20 72 ✔ ✔ ✔ - - - ✔ High clarity without plasticizers—ideal for extrusion Versaflex™ HC 3810 Series Translucent 20–90 0.88 16 54 - ✔ - - - ✔ - Formulated without animal derivatives, excellent colorability—ideal for seals and labware Versaflex™ G2705 N Translucent 60 0.89 20 - ✔ ✔ ✔ - PP ✔ ✔ High resiliance, low compression set, and good puncture sealing Versalloy™ HC 9220-70 Natural 70 0.95 17 51 - ✔ - - PP ✔ ✔ High temperature resistance Versalloy™ HC 9210 Series Natural 55 & 70 0.89 20 44 - - ✔ - - ✔ - Formulated without animal derivatives— ideal for injection molding long thin flow paths, smooth surface aesthetics Versaflex™ CL2242 Clear 43 0.89 23 - ✔ ✔ ✔ - - ✔ - High clarity maintained after boiling cleaning processes Versaflex™ CL2250 Clear 50 0.89 20 - ✔ ✔ ✔ - - ✔ - High clarity maintained after boiling cleaning processes FEATURED TPES FOR HEALTHCARE APPLICATIONS H EALTH CAR E GENERAL PROPERTIES REGULATORY BONDING PROCESS FEATURES Appearance Hardness Specific Gravity Weatherability* VOC FOG Odor** UL 94 Suitable Substrates Injection Extrusion ASTM Shore A ASTM (D792) Internal QUV 1000hrs (Delta E) VDA 278 μg/g (ppm) VDA 278 μg/g (ppm) Recycled Content Series reSound™ REC OF 7310-80 Black/ Natural (Gray) 80 0.90 0.35 75 379 3 (VDA 270) - PP ✔ 35% PCR/PIR content (food packaging)— ideal for automotive interior applications reSound™ REC OF 7310-90 Black/ Natural (Gray) 90 0.91 0.11 160 557 3 (VDA 270) - PP ✔ 45% PCR/PIR content (food packaging)— ideal for automotive interior applications General Purpose Series OnFlex™ G7705 B Black 42 1.20 - - - - - PP ✔ ✔ Easy processing for a wide variety of applications OnFlex™ G7705 N Natural 44 1.18 - - - - - PP ✔ ✔ Easy processing for a wide variety of applications OnFlex™ G7720 B Black 57 1.16 0.55 - - - HB PP ✔ ✔ Easy processing for a wide variety of applications OnFlex™ G7720 N Natural 55 1.17 3.72 - - - HB PP ✔ ✔ Easy processing for a wide variety of applications OnFlex™ G7820 N Natural 92 1.14 - - - - - PP ✔ ✔ Easy processing for a wide variety of applications Automotive Fasteners & Interior Components OnFlex™ AF 7210 Series Natural 40–90 1.00 - - - - - PP ✔ - Low odor and good UV resistance OnFlex™ AF 7210 Black 40 1.00 0.49 113 845 2 (SAE J1351, Dry) - PP ✔ - Low odor and good UV resistance OnFlex™ AF 7210 Black 50 1.00 0.42 51 762 2 (SAE J1351, Dry) - PP ✔ - Low odor and good UV resistance OnFlex™ AF 7210 Black 60 1.00 0.21 112 1740 1 (SAE J1351, Dry) - PP ✔ - Low odor and good UV resistance OnFlex™ AF 7210 Black 70 0.99 0.22 105 1976 3 (SAE J1351, Dry) - PP ✔ - Low odor and good UV resistance OnFlex™ AF 7210 Black 80 1.00 0.32 74 4459 3 (SAE J1351, Dry) - PP ✔ - Low odor and good UV resistance OnFlex™ AF 7210 Black 90 1.00 - - - - - PP ✔ - Low odor and good UV resistance HVAC & Interior Components OnFlex™ LO 7120-45N Natural 45 1.15 3.21 41 521 2 (SAE J1351, Dry) - PP ✔ - Significant reductions in VOCs and fogging compared to traditional TPE technologies GLS™ TPEs with Antimicrobial Technologies OnFlex™ LO 7120-45B AM Black 45 1.13 0.52 - - - - PP ✔ - Imbedded antimicrobial technology FEATURED TPES FOR TRANSPORTATION APPLICATIONS TRAN SPO RTATIO N * Values were taken on 3mm plaques following 1000hrs of continious exposure to UVA-340 ** Samples were conditioned at 23C at 35% RH for 24 hrs.

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.