| Climate Salad | Sydney, New South Wales | Visit site |
| Climate Scale | Brussels, Brussels-Capital | Visit site |
| Climate TRACE | Earth City, Missouri | Visit site |
| Climate X | London, England | Visit site |
| Climatize | Santa Cruz, California | Visit site |
| Closed Loop Partners | New York, New York | Visit site |
| Cloudberry Clean Energy | Oslo, Oslo | Visit site |
| Clough | Western Australia | Visit site |
| Clune Construction Company | Chicago, Illinois | Visit site |
| Clutch | Rancho Cordova, California | Visit site |
| Clúster Energético de Nuevo León | Monterrey, Nuevo León | Visit site |
| Clúster de l'Energia Eficient de Catalunya | Barcelona, Barcelona | Visit site |
| Cnlinko Industrial Solutions | Shenzhen Shi, Guangdong | Visit site |
| Coalfield Development Corporation | Huntington, West Virginia | Visit site |
| Coastal Energy | Fort Myers, Florida | Visit site |
| Coastal Solar | Hinesville, Georgia | Visit site |
| Coastwide Solar | Gold Coast, Queensland | Visit site |
| Cobra Wire & Cable | Hatboro, Pennsylvania | Visit site |
| Cobreflex Condutores Elétricos | Jandira, São Paulo | Visit site |
| Cochran | Seattle, Washington | Visit site |
| Code Red Safety | La Porte, Texas | Visit site |
| CodeGreen | New York, New York | Visit site |
| Coffman Engineers | Seattle, Washington | Visit site |
| Cogenfin | Forest, Brussels-Capital | Visit site |
| Cogengreen | Namur, Namur | Visit site |
| Cogeninfra | Borgaro Torinese, Turin | Visit site |
| Coherix | Ann Arbor, Michigan | Visit site |
| Colgas | Bogotá, Bogotá | Visit site |
| Colliers Engineering & Design | Holmdel, New Jersey | Visit site |
| Colorado Mountain Builders | Woodland Park, Colorado | Visit site |
| Colorado Mountain Solar | Buena Vista, Colorado | Visit site |
| Colorado Renewable Energy Society (CRES) | Fort Collins, Colorado | Visit site |
| Colorado Solar and Storage Association (COSSA) | Denver, Colorado | Visit site |
| Columbia Basin Trust | Castlegar, British Columbia | Visit site |
| Columbia Electric, Inc. | San Leandro, California | Visit site |
| Com-Cavi | Napoli, Naples | Visit site |
| ComAp Group | Praha, Prague | Visit site |
| ComEd | Niles, Illinois | Visit site |
| ComOps B.V. | Lijnden, North Holland | Visit site |
| ComfortZone AB | Täby, Stockholm | Visit site |
| Comis S.r.l. | Pesaro, Pesaro and Urbino | Visit site |
| Commerce Coating Services Inc | Carson, California | Visit site |
| Commercial Solar Panel Recycling | Phillipsburg, New Jersey | Visit site |
| Commonwealth Electrical Technologies | Worcester, Massachusetts | Visit site |
| Community Energy England | Sheffield, England | Visit site |
| Community Solar Enroll US - Your Gateway to Renewable Energy | Alexander, Maine | Visit site |
| Compact Syngas Solutions Limited | Deeside, Wales | Visit site |
| CompanyCam | Lincoln, Nebraska | Visit site |
| Compass Lexecon | Washington, District of Columbia | Visit site |
| Competitive Edge Partners & Consulting, LLC | Altamonte Springs, Florida | Visit site |
| Complete System Fabrication, LLC | Springtown, Texas | Visit site |
| Comprehensive Energy Services, Inc. | Longwood, Florida | Visit site |
| Compto Energies Renouvelables | بن عروس, Ben Arous | Visit site |
| Comstock Metals | Silver Springs, Nevada | Visit site |
| Comunità Energetiche S.p.A. | Terni, Terni | · |
| Con Edison Clean Energy Businesses | Valhalla, New York | Visit site |
| Con4Mare | Hamburg, Hamburg | Visit site |
| Concentric Energy Advisors | Marlborough, Massachusetts | Visit site |
| Concord Energy Strategies, LLC | Louisville, Kentucky | Visit site |
| Condon-Johnson & Associates, Inc. | Oakland, California | Visit site |
| Conduct Technical Solutions | Barendrecht, South Holland | Visit site |
| Conductor Power | Baxter, Minnesota | Visit site |
| Cone Drive (Jiangsu) Power Transmission Co., LTD | Traverse City, Michigan | Visit site |
| ConfirmWare | Hangzhou, Zhejiang | Visit site |
| Confluence Compliance Companies, LLC | Grand Junction, Colorado | Visit site |
| Conifer | Sunnyvale, California | Visit site |
| Conloop GmbH | Freiburg im Breisgau, Baden-Württemberg | Visit site |
| ConnectDER | Philadelphia, Pennsylvania | Visit site |
| Connecticut Green Bank | Hartford, Connecticut | Visit site |
| Connecticut Roundtable on Climate and Jobs | Hartford, Connecticut | Visit site |
| Conroe Machine | Conroe, Texas | Visit site |
| Consnant Technology | Shenzhen Shi, Guangdong | Visit site |
| Consolidated Contractors Company | Amarousio, Attica | Visit site |
| Consolidated Power Projects | Adelaide, South Australia | Visit site |
| Constellation | Baltimore, Maryland | Visit site |
| Constructiv | Brussels, Brussels-Capital | Visit site |
| Constructive Operations | Phoenix, AZ | Visit site |
| Contact Solar LTD | Chorley, England | Visit site |
| Contegra Construction Co. | Edwardsville, Illinois | Visit site |
| Contemporary Amperex Technology Hungary Kft. | Debrecen, Hajdú-Bihar | Visit site |
| Contendre Greenergy Limited | Mumbai, Maharashtra | Visit site |
| Continental Electrical Construction Co. | Oak Brook, Illinois | Visit site |
| Continuum Environmental Services Ltd. | Richfield, Ohio | Visit site |
| ContourGlobal | Milano, Milan | Visit site |
| Contract Land Staff | Sugar Land, Texas | Visit site |
| ContractPower | San Marcos, California | Visit site |
| Contractors Edge | San Diego, California | Visit site |
| Control Air Enterprises LLC | Anaheim, California | Visit site |
| ConverterTec | Kempen, North Rhine-Westphalia | Visit site |
| CoolSys Energy Solutions | Brea, California | Visit site |
| Coolpower Electrical | Harlow, England | Visit site |
| Copenhagen Infrastructure Partners | Nordhavn, Capital Region of Denmark | Visit site |
| Copenhagen Infrastructure Service Co. | København, Capital Region of Denmark | Visit site |
| Coperniq | San Francisco, California | Visit site |
| Copperline Electric, Inc. | Tampa, Florida | Visit site |
| Copperweld | Brentwood, Tennessee | Visit site |
| Cor-Ray Painting Co. | Santa Fe Springs, California | Visit site |
| CorSolar | São Paulo, São Paulo | Visit site |
| Corab | Olsztyn, Warmian-Masurian Voivodeship | Visit site |
| Cordeel Belgium | Temse, East Flanders | Visit site |
| Cordeiro Soluções em Energia | São Paulo, São Paulo | Visit site |
| Core Solar LLC | Austin, Texas | Visit site |
| CoreComm SI | Veszprém, Veszprém | Visit site |
| CorePack Renewable Energy | Nepean, Ontario | Visit site |
| Coreshell | Oakland, California | Visit site |
| Corigy Solar | Xiamen Shi, Fujian | Visit site |
| Corsa Strategies | Indianapolis, Indiana | Visit site |
| Cory | London, England | Visit site |
| Cosedil S.p.A | Santa Venerina, Catania | Visit site |
| Cosmos Innovation | Singapore, Central Singapore Community Development Council | Visit site |
| Cotter Consulting, Inc. (now Consertus) | Chicago, Illinois | Visit site |
| Couleenergy | Ningbo Shi, Zhejiang | Visit site |
| Craft Solar | Novato, California | Visit site |
| Create Energy, LLC | Portland, TN | Visit site |
| Crest Industries | Pineville, Louisiana | Visit site |
| Crete United | Charlotte, North Carolina | Visit site |
| Crimson Renewable Energy | Denver, Colorado | Visit site |
| Crisil | Mumbai, Maharashtra | Visit site |
| Cross Country Infrastructure Services | Aurora, Colorado | Visit site |
| Cruden Group | Edinburgh, Scotland | Visit site |
| Cuadristas Serca | Alcalá de Henares, Madrid | Visit site |
| Cubenergy | Düsseldorf, North Rhine-Westphalia | Visit site |
| Cummins Latin America | · | Visit site |
| Curenta | City of Industry, California | Visit site |
| Current Home | Hemet, California | Visit site |
| Current Hydro | Pittsburgh, Pennsylvania | Visit site |
| Current Renewables Engineering Inc. | Riverside, California | Visit site |
| Currie & Brown | London, England | Visit site |
| Cworth Energy | Guangzhou Shi, Guangdong | Visit site |
| Cyber Energia | Denver, Colorado | Visit site |
| CyberDax Solar Company Ltd. | Shenzhen Shi, Guangdong | Visit site |
| CyberPower | Shakopee, Minnesota | Visit site |
| Cybertrol Engineering | Maple Grove, Minnesota | Visit site |
| Cybrid Technologies Inc. | Suzhou Shi, Jiangsu | Visit site |
| Cycle Momentum | Montréal, Quebec | Visit site |
| CycleSolar | Austin, Texas | Visit site |
| Cygni Energy | Hyderabad, Telangana | Visit site |
| Cypress Environmental Consulting | Houston, Texas | Visit site |
| careNext | Brentwood, Tennessee | Visit site |
| cellcentric GmbH & Co. KG | Kirchheim unter Teck, Baden-Württemberg | Visit site |
| competence.hub | Advanced Nuclear Fuels GmbH | Lingen, Lower Saxony | Visit site |
| crino GmbH | München, Bavaria | Visit site |