| Capitol Valley Electric | Sacramento, California | Visit site |
| Capra Energy Solutions - Helical Piers | Irving, Texas | Visit site |
| Capra Group | Billings, Montana | Visit site |
| Capriole Construction Company L.L.C. | Dubai, Dubai | Visit site |
| Captain Power | Beltsville, Maryland | Visit site |
| Captiva Asset Management | Oslo, Oslo | Visit site |
| Captivate Technology | Palmerston North, Manawatū-Whanganui | Visit site |
| Captura | Pasadena, California | Visit site |
| Capwatt | Guarulhos, São Paulo | Visit site |
| Capwell Services | Houston, Texas | Visit site |
| Carbice | Atlanta, Georgia | Visit site |
| Carbogenesis | Miami, Florida | Visit site |
| Carbon3 | Singapore, Central Singapore Community Development Council | Visit site |
| CarbonQuest | New York, New York | Visit site |
| CarbonRun | Dartmouth, Nova Scotia | Visit site |
| Carbonade | Dimona, Southern District | Visit site |
| Carcinus Ltd | Eastleigh, England | Visit site |
| Cardinal Engineering Consultant Pvt. Ltd. | Ahmedabad, Gujarat | Visit site |
| Carey Electric, Inc. | Watervliet, New York | Visit site |
| Carlo Gavazzi Automation | Lainate, Milan | Visit site |
| Carlo Maresca | Pescara, Pescara | Visit site |
| Carlson Software | Maysville, KY | Visit site |
| Carnegie Clean Energy | Perth, Western Australia | Visit site |
| Carolina Motion Controls | Greenville, South Carolina | Visit site |
| Carport Structures | Oxford, Michigan | Visit site |
| Carroll Daniel | Gainesville, Georgia | Visit site |
| Carter Complete Building Services Ltd | Stoke-on-Trent, England | Visit site |
| Cartflow S.r.l. | Napoli, Naples | Visit site |
| Casais Angola | Luanda, Luanda | Visit site |
| Casais Construction | Mire de Tibães, Braga | Visit site |
| Cascade Energy | Portland, Oregon | Visit site |
| Cascadia Motion | Portland, Oregon | Visit site |
| Cascara Energy | Roquetas de Mar, Almería | Visit site |
| Cases & Lacambra | Barcelona | Visit site |
| Castaways Energy | Christmas, Florida | Visit site |
| Castillo Engineering | Maitland, Florida | Visit site |
| Castle Contracting | Webster Groves, Missouri | Visit site |
| Castle Surveys Ltd | Ashby-de-la-Zouch, England | Visit site |
| Castrol | Reading, England | Visit site |
| Catalyst | Dublin, Dublin | Visit site |
| Catapult Network | London, England | Visit site |
| Cathedral Land Solutions LLC | Aurora, Colorado | Visit site |
| Cbus Super Fund | Melbourne, Victoria | Visit site |
| Cecil | Sydney, New South Wales | Visit site |
| Cecilia | Jersey City, New Jersey | Visit site |
| Cedar Creek Renewables, LLC | Hedrick, Iowa | Visit site |
| Cefic | Brussels, Brussels-Capital | Visit site |
| CelLink Corporation | San Carlos, California | Visit site |
| Celestial Renewexperts LLP | Pune, Maharashtra | Visit site |
| Celestica | Toronto, Ontario | Visit site |
| CellBlock FCS | Standish, Maine | Visit site |
| CellCircle | Würzburg, Bavaria | Visit site |
| Cellula Robotics Ltd. | Burnaby, British Columbia | Visit site |
| Celtic Bank | Salt Lake City, Utah | Visit site |
| Cengiz Holding | Üsküdar, Istanbul | Visit site |
| Cenovus Energy | Calgary, Alberta | Visit site |
| CenterPoint Energy | Houston, Texas | Visit site |
| Central Electricity Regulatory Commission (CERC) | New Delhi, Delhi | Visit site |
| Central Hudson | Poughkeepsie, New York | Visit site |
| Central Maine Power Company | · | Visit site |
| Central Steel Build | Kyneton, Victoria | Visit site |
| Centre for Sustainable Energy | Bristol, England | Visit site |
| Centro Energy | Changzhou Shi, Jiangsu | Visit site |
| Centro Tecnológico EnergyLab | Vigo, Pontevedra | Visit site |
| Centrum Wiskunde & Informatica | Amsterdam, North Holland | Visit site |
| Centum Electronics Ltd. | Bengaluru, Karnataka | Visit site |
| Cenvar Roofing & Solar | Lynchburg, Virginia | Visit site |
| Cenviro Group | Kuala Lumpur, Kuala Lumpur | Visit site |
| Ceramatec, Inc. | · | Visit site |
| Cerberus Capital Management | New York, New York | Visit site |
| CertainTeed | Malvern, Pennsylvania | Visit site |
| Certified Slings & Supply | Casselberry, Florida | Visit site |
| Cesbe Engenharia | Curitiba, Paraná | Visit site |
| Cetogenix | Rotorua, Bay of Plenty | Visit site |
| Ceyone Engineering Services | Greater Noida, Uttar Pradesh | Visit site |
| Chain Electric Company | Hattiesburg, Mississippi | Visit site |
| Chandos Construction | Edmonton, Alberta | Visit site |
| Changeworks | Edinburgh, Scotland | Visit site |
| Changfeng Wire & Cable | Hebei | Visit site |
| CharIN e.V. | Berlin, Berlin | Visit site |
| ChargePodX | Carson, California | Visit site |
| ChargerHelp | Los Angeles, California | Visit site |
| Chargerly | Lysaker, Akershus | Visit site |
| Charter Development, LLC | Charlottesville, Virginia | Visit site |
| Chem Link | Schoolcraft, Michigan | Visit site |
| Chemix, Inc. | Sunnyvale, California | Visit site |
| Chemonics Egypt Consultants | Giza, Giza | Visit site |
| Chemonics International | Washington, District of Columbia | Visit site |
| Chengdu Sixpence Technology Co., Ltd. | Sichuan | Visit site |
| Cherne Contracting Corporation | Eden Prairie, Minnesota | Visit site |
| Chestnut Carbon | New York, New York | Visit site |
| Chiko Solar | Shanghai, Shanghai | Visit site |
| Chikousa | Buckeye, Arizona | Visit site |
| China Datang Corp Renewable Power Co Ltd | Beijing, Beijing | Visit site |
| China Energy Engineering Group Co. Ltd. | Beijing, Beijing | Visit site |
| China-Manufacturer | Guangdong | Visit site |
| Chint Cable | Bathinda, Punjab | Visit site |
| Chloris Geospatial | Boston, Massachusetts | Visit site |
| Chronicle Heritage | Phoenix, Arizona | Visit site |
| Cielo WiGle Inc. | Bellevue, Washington | Visit site |
| Ciera Group | Calgary, Alberta | Visit site |
| Cinterra | Hope Mills, North Carolina | Visit site |
| Circu Li-ion | Ludwigshafen am Rhein, Rhineland-Palatinate | Visit site |
| Circulair Friesland | Leeuwarden, Friesland | Visit site |
| Circutor | Sabadell, Barcelona | Visit site |
| Citadel Roofing & Solar | Vacaville, California | Visit site |
| Citel Electronics GmbH | Neuss, North Rhine-Westphalia | Visit site |
| Citel Inc. | Miramar, Florida | Visit site |
| Citus Power | Sarıyer, Istanbul | Visit site |
| City of Amsterdam | Dunabogdány, Pest | Visit site |
| City of Austin | Austin, Texas | Visit site |
| City of Edmonton | Edmonton, Alberta | Visit site |
| City of Riverside | · | Visit site |
| City of Toronto | Toronto, Ontario | Visit site |
| CityTec | Alblasserdam, South Holland | Visit site |
| Civ Robotics | San Francisco, California | Visit site |
| Clamore Solar Eswatini | Mbabane, Hhohho - Mbabane | Visit site |
| Clark Construction Company | Lansing, Michigan | Visit site |
| Clark Construction Group | Bethesda, Maryland | Visit site |
| Clayco | Chicago, Illinois | Visit site |
| Clean Energy Associates (CEA) | Allen, Texas | Visit site |
| Clean Energy Association of British Columbia (CEBC) | Vancouver, British Columbia | Visit site |
| Clean Energy Economy MN (CEEM) | Minneapolis, Minnesota | Visit site |
| Clean Energy Pipeline | London, England | Visit site |
| Clean Grid Alliance | Saint Paul, Minnesota | Visit site |
| Clean Power Hour | Kansas, Illinois | Visit site |
| Clean Power Research | Bellevue, Washington | Visit site |
| CleanAI Initiative | Toronto, Ontario | Visit site |
| CleanIQ | Komotini, Eastern Macedonia and Thrace | Visit site |
| CleanSwitch | Albuquerque, New Mexico | Visit site |
| Cleanearth | Lashibi, Greater Accra | Visit site |
| Cleanleaf Energy | Irving, Texas | Visit site |
| Cleantech Commons™ | Peterborough, Ontario | Visit site |
| Cleantech Law Partners | San Francisco, California | Visit site |
| Cleantech San Diego | San Diego, California | Visit site |
| ClearBlue Markets | Toronto, Ontario | Visit site |
| ClearGen Holdings LLC | Charlotte, North Carolina | Visit site |
| Clearloop | Brentwood, Tennessee | Visit site |
| Cleco | Pineville, Louisiana | Visit site |
| Clemens Kraft AS | Oslo, Oslo | Visit site |
| Clemessy | Mulhouse, Haut-Rhin | Visit site |
| Clenergy | Melbourne, Victoria | Visit site |
| Cleveland Cable | Leeds, England | Visit site |
| Cleveland-Cliffs | Cleveland, Ohio | Visit site |
| ClimEtSan-OnTheGround | Bonn, North Rhine-Westphalia | Visit site |
| Climacool by Blue Pearl Energy | La Boisse, Ain | Visit site |
| Climagea | Pomezia, Rome | Visit site |
| Climate Council | · | Visit site |
| Climate Finance Solutions | Arcata, California | Visit site |
| Climate Group | London, England | Visit site |