| Cliftonville Homes Ltd | Construction | 2017 |
| Clinic Clubhouse Limited | Other services | 2024 |
| Clinical DI Limited | Administrative & support | 2025 |
| Clinical Healthcare Services Ltd | Health & social care | 2023 |
| Clinicians Innovation Associates Ltd | Health & social care | 2016 |
| Clinilinx Limited | Financial services | 2018 |
| Clive Tait Consulting Services Limited | Professional & scientific | 2017 |
| CLM Waste Management Ltd | Water & waste | 2021 |
| Clocktower Contracts Limited | Administrative & support | 2005 |
| Clodaken Limited | Health & social care | 2014 |
| Cloonfinish Electrical Ltd | Construction | 2016 |
| Clothes AID Limited | Other services | 2017 |
| Cloud Combinator Ltd | Information & communication | 2023 |
| Cloud Point Holdings Limited | Real estate | 2021 |
| Cloudpics Ltd | Professional & scientific | 2023 |
| Cloudrunner Games Ltd | Information & communication | 2022 |
| CLOUDY2CLEAR London East Ltd | Wholesale & retail | 2017 |
| CLP Landscapes Ltd | Administrative & support | 2025 |
| Clsl 2023 Limited | Administrative & support | 2013 |
| Club Flexx Ltd | Arts & recreation | 2026 |
| CLUB28CAPITAL Limited | Financial services | 2023 |
| Clubadminpro Ltd | Information & communication | 2019 |
| Cluckingamazing Ltd | Hospitality | 2025 |
| Clueue Limited | Information & communication | 2015 |
| Clyngroup Limited | Administrative & support | 2020 |
| CM Construction and Civil Engineering Ltd | Construction | 2014 |
| CM Strategic 613 Limited | Financial services | 2021 |
| CM14 Management Limited | Households | 2018 |
| CM2 Industrial Services Ltd | Extraterritorial | 2016 |
| Cmcce Limited | Administrative & support | 2019 |
| CMM Engineering Solutions Ltd | Professional & scientific | 2023 |
| CMS Electrical Engineering Limited | Construction | 2018 |
| CMS Energy Ltd | Construction | 2026 |
| Cmx&Co Ltd | Professional & scientific | 2024 |
| Cmxperience Ltd. | Professional & scientific | 2017 |
| CNS Communications Limited | Administrative & support | 2009 |
| Coachlease Limited | Financial services | 1997 |
| Coachwork Repair Services Ltd | Wholesale & retail | 2022 |
| Coam Ltd | Information & communication | 2022 |
| Coast and Kitchen Ltd | Wholesale & retail | 2021 |
| Coast Exchange Ltd | Information & communication | 2018 |
| Coastal Consulting Services Limited | Professional & scientific | 2019 |
| Cobalt Logistics Ltd | Transport & logistics | 2018 |
| Cobdens Property Ltd | Real estate | 2019 |
| Cockney Pride C.I.C. | Education | 2018 |
| Coco Lighting Limited | Manufacturing | 2002 |
| Code Preview Ltd | Information & communication | 2022 |
| Codham Hall (Holdings) Limited | Real estate | 2023 |
| Codham Hall Estates Limited | Real estate | 2013 |
| Coffee Squared Limited | Hospitality | 2016 |
| Cognetivity Ltd | Professional & scientific | 2013 |
| Cognially Services Ltd | Information & communication | 2026 |
| Cognostiq Ltd | Information & communication | 2021 |
| Cohen Bailey & Associates Ltd | Professional & scientific | 2015 |
| Cokasobi Limited | Health & social care | 2016 |
| Colanis Commerce Ltd | Wholesale & retail | 2019 |
| Colanis Health Ltd | Wholesale & retail | 2026 |
| Cole Family Ltd | Financial services | 2018 |
| Cole Martin Tregaskis Ltd | Health & social care | 2010 |
| Colin H. Hellier Limited | Manufacturing | 1992 |
| Colin Power Limited | Construction | 2021 |
| Collaboradoodle Limited | Professional & scientific | 2026 |
| Collective Cars Limited | Wholesale & retail | 2021 |
| Collier ROW Tyre Services Limited | Wholesale & retail | 1980 |
| Collins & Curtis Masonry Limited | Manufacturing | 1999 |
| Colman Estates Ltd | Real estate | 2026 |
| Colman Inc Ltd | Professional & scientific | 2021 |
| Colmin Limited | Wholesale & retail | 2025 |
| Colnesett Limited | Administrative & support | 2013 |
| Colourway Care Ltd | Health & social care | 2023 |
| Colton Electrical Equipment Co.Limited | Manufacturing | 1937 |
| Columbus Flooring Ltd | Construction | 2009 |
| Columbus Garden Solutions Limited | Administrative & support | 2015 |
| Columbus Landscaping Limited | Administrative & support | 2019 |
| Column Test Limited | Manufacturing | 2006 |
| Combat Trophies Limited | Wholesale & retail | 2017 |
| Comluge Property Limited | Wholesale & retail | 2024 |
| Commercial Catering Installations Ltd | Manufacturing | 2020 |
| Commlite Ltd | Extraterritorial | 2011 |
| Common Earth | Professional & scientific | 2018 |
| Compass FM Ltd | Administrative & support | 2025 |
| Compeer Limited | Professional & scientific | 1993 |
| Complete Construction Essex Ltd | Construction | 2023 |
| Complete Contractor Services Ltd | Construction | 2019 |
| Complete R Soles Ltd | Real estate | 2025 |
| Complete Recovery Solutions Ltd | Other services | 2024 |
| Completed Services Limited | Water & waste | 2022 |
| Complevit Ltd | Information & communication | 2017 |
| Complex Electrical Services Ltd | Construction | 2015 |
| Compliance Guide Limited | Information & communication | 2026 |
| Comptrek (UK) Limited | Wholesale & retail | 2025 |
| Comtec (Essex) Limited | Wholesale & retail | 1991 |
| Comunity Systems Holdings Limited | Financial services | 2024 |
| Comunity Systems Limited | Wholesale & retail | 2015 |
| Conbella Creative Solutions Ltd | Professional & scientific | 2018 |
| Concause Limited | Financial services | 2024 |
| Concept Carpentry & Construction Ltd | Construction | 2022 |
| Concept Carton Limited | Professional & scientific | 2023 |
| Concertino Limited | Education | 2018 |
| Condor Cloud Consulting Limited | Information & communication | 2025 |