| Codefour Solutions Limited | Information & communication | 2000 |
| Coffee Snobs Ltd | Hospitality | 2004 |
| Coggi Technologies Limited | Information & communication | 2019 |
| Coghlan Lodges Limited | Health & social care | 2009 |
| Cohobblopot Limited | Hospitality | 2019 |
| Coinmedia Limited | Information & communication | 2017 |
| Cold Formed UK Ltd | Manufacturing | 2023 |
| Coldgrove Estates Ltd | Real estate | 2025 |
| Cole Miller Consulting Limited | Administrative & support | 2008 |
| Colemans Moor Heights Ltd | Real estate | 2024 |
| Colin Hellmuth Investments Limited | Extraterritorial | 2015 |
| Colin Mear Engineering Limited | Manufacturing | 1982 |
| Colin Mear Limited | Manufacturing | 2010 |
| Colin's Country Club Limited | Other services | 2021 |
| Coll Holdings Limited | Financial services | 2025 |
| Collector Shores Ltd | Wholesale & retail | 2023 |
| Coln ST Aldwyn Properties Limited | Real estate | 1994 |
| Colours of Integrity Limited | Construction | 2009 |
| Command Rooms Ltd | Administrative & support | 2020 |
| Commercial Acceleration Ltd | Professional & scientific | 2017 |
| Commercial Effectiveness Consultancy Limited | Professional & scientific | 2011 |
| Common Language Limited | Professional & scientific | 2024 |
| Commonwealth East Ltd | Construction | 2026 |
| Commonwealth WAR Graves Enterprises Limited | Hospitality | 2025 |
| Commonwood Manor Apart Hotel Ltd | Construction | 2025 |
| Community Build (Maidenhead) Community Interest Company | Financial services | 2024 |
| Community Cooperation UK Wide CIC | Professional & scientific | 2024 |
| Compact Cases Limited | Water & waste | 1965 |
| Compagnie Francaise D'Electricite ET DE Maintenance Ltd | Construction | 2004 |
| Compair Limited | Professional & scientific | 1935 |
| Compass Electrical Engineering Limited | Construction | 2022 |
| Compass Surveys Limited | Professional & scientific | 2020 |
| Compelite Ltd | Information & communication | 2015 |
| Compete Impossible Ltd | Information & communication | 2020 |
| Complete Circle Support Ltd | Professional & scientific | 2018 |
| Complete Cleaning 24/7 Limited | Administrative & support | 2016 |
| Complete Fleet Services Ltd | Administrative & support | 2004 |
| Complete Janitorial Supplies Limited | Wholesale & retail | 2011 |
| Complete Rubbish Ltd | Water & waste | 2020 |
| Complexity Services Ltd | Construction | 2017 |
| Comsense Ltd | Information & communication | 2021 |
| Conbloc Limited | Professional & scientific | 1989 |
| Conco Ventures Ltd | Wholesale & retail | 2020 |
| Concord Fabrics (UK) Limited | Manufacturing | 1999 |
| Concordant Systems Limited | Information & communication | 2002 |
| Concrete Pump Services Limited | Construction | 2016 |
| Conductify Limited | Administrative & support | 2020 |
| Conexus Services Ltd | Information & communication | 2017 |
| Conference Contacts Events Limited | Professional & scientific | 2019 |
| Conference Contacts Limited | Administrative & support | 1987 |
| Connect Strategic Communications Ltd | Professional & scientific | 2024 |
| Connected Customers Ltd | Information & communication | 2013 |
| Connected Networks Limited | Information & communication | 2017 |
| Connected World Properties Ltd | Real estate | 2019 |
| Connected World Technologies Ltd | Information & communication | 2017 |
| Connell Construction Limited | Construction | 2023 |
| Conquer AI Limited | Professional & scientific | 2025 |
| Conradcare Ltd | Health & social care | 2022 |
| Conscious Catering Limited | Manufacturing | 2019 |
| Conscious Create Ltd | Information & communication | 2017 |
| Consensys Systems UK Limited | Information & communication | 2017 |
| Consider Culture Limited | Professional & scientific | 2026 |
| Constance & Co Limited | Information & communication | 2014 |
| Consult Bear Ltd | Professional & scientific | 2023 |
| CONSULT4 Limited | Professional & scientific | 2023 |
| Consulting Business Ltd | Wholesale & retail | 2015 |
| Consumer Fluent Group Ltd | Professional & scientific | 2013 |
| Consumer Fluent Ltd | Professional & scientific | 2019 |
| Continental Print Associates Limited | | 1960 |
| Contoro Limited | Information & communication | 2013 |
| Contract Van Hire Ltd | Administrative & support | 2022 |
| Control Design Solutions Limited | Professional & scientific | 2023 |
| Control Solutions (UK) Limited | Professional & scientific | 2013 |
| Convergence Pharmaceuticals Holdings Limited | Professional & scientific | 2011 |
| Convergence Pharmaceuticals Limited | Professional & scientific | 2015 |
| Cook's Street Limited | Hospitality | 2018 |
| Cookham Design Partnership Limited | Construction | 2018 |
| Cookham Locals Ltd | Wholesale & retail | 2023 |
| Cookham Nails Bar Limited | Other services | 2019 |
| Cookham Riding School Ltd. | Arts & recreation | 2007 |
| Cookham Road Residents (Maidenhead) Limited | Real estate | 1976 |
| Cookmansulting 2 Limited | Professional & scientific | 2025 |
| Cooper Antennas Ltd | Manufacturing | 2005 |
| Copas Brothers (Construction) Limited | Construction | 2017 |
| Copas Holdings Limited | Real estate | 2024 |
| Copas Partnership Limited | Real estate | 2024 |
| Copas Traditional Turkeys Limited | Manufacturing | 1999 |
| Cope Design Associates Limited | Arts & recreation | 1974 |
| Copper Tree Productions Limited | Information & communication | 2010 |
| Coralz Ltd | Agriculture & fishing | 2019 |
| Cordwallis Commercials (Maidenhead) Limited | Wholesale & retail | 1970 |
| Cordwallis Vehicle Contracts Limited | Wholesale & retail | 2015 |
| Core and Coat Limited | Wholesale & retail | 2026 |
| Core Commercial Construction Ltd | Construction | 2024 |
| Core Connexion Ltd | Arts & recreation | 2022 |
| Core Connexion Retreats Ltd | Arts & recreation | 2024 |
| Core Forme Ltd | Other services | 2025 |
| Core Swim Ltd | Wholesale & retail | 2015 |
| Corecompass Ltd | Professional & scientific | 2023 |
| Coredis Limited | Information & communication | 2009 |