| Cheers to Chaii Ltd | Hospitality | 2026 |
| Chef's Table Solutions Limited | Hospitality | 2011 |
| Cherimoya Limited | Information & communication | 1999 |
| Chignell Betting Integrity Solutions Ltd | Other services | 2024 |
| Child Rescue Coalition EU | Information & communication | 2016 |
| Chinese Red Dog AID UK | Other services | 2024 |
| Chloe Ward & Co Ltd | Professional & scientific | 2026 |
| Chockateau Ltd | Manufacturing | 2025 |
| Chris Sales Fork Lift Truck Training Limited | Transport & logistics | 2006 |
| Cidek Consulting Limited | Professional & scientific | 2021 |
| Cilla Black Limited | Professional & scientific | 2009 |
| Cilm Limited | Households | 2020 |
| Circle-Assets Ltd | Extraterritorial | 2023 |
| Citrus Rooms Beauty (ST Ives) Limited | Other services | 2016 |
| CJW Electrical and Data Solutions Ltd | Extraterritorial | 2006 |
| Claire Denton Beauty Ltd | Other services | 2021 |
| Clapham Park Management Company Limited | Professional & scientific | 1996 |
| Claret IT Consultants Limited | Information & communication | 2016 |
| Clarity Care Providers Ltd | Health & social care | 2012 |
| Clarity Health and Beauty Ltd. | Other services | 2012 |
| Clark Services Limited | Professional & scientific | 2016 |
| Class Construction and Property Services Ltd | Construction | 2020 |
| Classique Cleaners Limited | Administrative & support | 2016 |
| Claylands Holdings Limited | Agriculture & fishing | 1995 |
| Clearview Builders Limited | Construction | 2018 |
| Clearview Technology Solutions Ltd | Information & communication | 2021 |
| Clevercraft Plumbing Ltd | Construction | 2025 |
| Climatise Solutions Ltd | Construction | 1990 |
| Clinkers Arch Residents Association Limited | Households | 1984 |
| Clinton AF Properties Ltd | Real estate | 2025 |
| Clinton Windows Limited | Administrative & support | 2017 |
| Clover Global Ltd | Real estate | 2025 |
| CLUB66PRO Ltd | Education | 2022 |
| Clustric Limited | Information & communication | 2019 |
| CMA Property Consulting Limited | Professional & scientific | 2011 |
| CMC Biotech Consulting Ltd | Professional & scientific | 2024 |
| Cmrr Limited | Professional & scientific | 2002 |
| CNC Group Limited | Manufacturing | 2016 |
| Coach ID International Limited | Arts & recreation | 2020 |
| Cobley Agricultural Services Ltd | Agriculture & fishing | 2022 |
| Colbert Property Limited | Real estate | 2025 |
| Colney Island Studios Ltd | Information & communication | 2025 |
| Comtower Limited | Information & communication | 1998 |
| Concept Garage Ltd | Wholesale & retail | 2017 |
| Conexx Co UK Ltd. | Administrative & support | 2018 |
| Conformancex Ltd | Administrative & support | 2021 |
| Conkula Ltd | Administrative & support | 2025 |
| Connorfit Ltd | Public administration | 2025 |
| Consortia Ltd | Administrative & support | 2021 |
| Constratego Limited | Administrative & support | 2017 |
| Constructec Ltd | Construction | 2022 |
| Contrel Limited | Manufacturing | 1997 |
| Conversion Services ST Neots Ltd | Professional & scientific | 2024 |
| Conveypal Limited | Information & communication | 2021 |
| Cool Water Car Wash Ltd | Other services | 2024 |
| Cooper Beckwith Associates Limited | Real estate | 1997 |
| Cooper Beckwith Investments Ltd. | Real estate | 2020 |
| Copadi Ltd | Information & communication | 2017 |
| Cornerstone (ST Neots) Limited | Extraterritorial | 2010 |
| Cornfield Financials Ltd | Professional & scientific | 2013 |
| Correct Connect Ltd | Construction | 2019 |
| Corsa Contracting Ltd | Other services | 2024 |
| Cosi London Ltd | Wholesale & retail | 2024 |
| Cosma Investments Limited | Financial services | 2024 |
| Cosmic Dust Limited | Manufacturing | 2016 |
| Cosmosten Ltd | Other services | 2023 |
| Countryside Marquee Hire Limited | Construction | 2013 |
| Courtyard 58 Limited | Arts & recreation | 2025 |
| Covali Trans Ltd | Transport & logistics | 2014 |
| CPE International Limited | Financial services | 2023 |
| Cpimex Ltd | Agriculture & fishing | 2021 |
| CPX Property Ltd | Construction | 2025 |
| CR Window Cleaning Limited | Administrative & support | 2014 |
| Crafty Monkey Ltd | Wholesale & retail | 2023 |
| Craig Stone Welding Ltd | Manufacturing | 2016 |
| Crawford Lynn Limited | Professional & scientific | 2005 |
| Creativity Kitty Ltd | Arts & recreation | 2023 |
| Cricket East Limited | Arts & recreation | 2019 |
| Cromlech Care Services Limited | Administrative & support | 2024 |
| Cromwell Fire Limited | Manufacturing | 1994 |
| Cromwell Stock Ltd. | Real estate | 2020 |
| Cross Counties Construction Limited | Construction | 2016 |
| Crosshall Infant School Academy Trust | Education | 2010 |
| Crosshall Junior School Limited | Education | 2010 |
| Crosshall Marine Limited | Arts & recreation | 1980 |
| Crouch END Osteopaths Ltd | Health & social care | 2016 |
| Crown Luxurious Limited | Real estate | 2024 |
| Crownbridge Homes Ltd | Real estate | 2026 |
| Cs&Br Ltd | Hospitality | 2025 |
| Cubed Fusion Ltd | Administrative & support | 2022 |
| Cufflinks Ltd | Information & communication | 2025 |
| CURE4SOUL Ltd | Extraterritorial | 2021 |
| Curiously Divergent CIC | Administrative & support | 2025 |
| Cxgnss Limited | Information & communication | 2023 |
| Cybescape Ltd | Arts & recreation | 2024 |
| Cytropic Ltd | Information & communication | 2025 |
| Czech School Cambridge CIC | Education | 2019 |
| D Bell Consulting Ltd | Professional & scientific | 2023 |
| D P Services (ST Neots) Ltd | Construction | 2017 |
| D West & Sons Ltd | Construction | 2006 |