| Byrne Group Holdings Limited | Administrative & support | 2016 |
| Byroe Court Limited | Real estate | 2010 |
| BYT Associates Limited | Professional & scientific | 2020 |
| Bytefyre Limited | Professional & scientific | 2022 |
| BZ Holdings Limited | Financial services | 2025 |
| Büro Group Ltd | Construction | 2015 |
| C & E Recovery Limited | Administrative & support | 2008 |
| C & G Clark Limited | Construction | 2001 |
| C & L Engineering Limited | Professional & scientific | 2022 |
| C B F Advisory Limited | Professional & scientific | 2015 |
| C B Therapy Ltd | Health & social care | 2021 |
| C Davies Locums Limited | Professional & scientific | 2024 |
| C J a Build Ltd | Construction | 2018 |
| C J Lewis Joinery Limited | Construction | 2021 |
| C Jones Motor Engineers Limited | Financial services | 2011 |
| C Konsult Ltd | Professional & scientific | 2014 |
| C M Cannell Limited | Administrative & support | 2015 |
| C Plumb Ltd | Construction | 2005 |
| C Russell Consulting Limited | Professional & scientific | 2023 |
| C S Barton Limited | Arts & recreation | 2008 |
| C Tierney Services Ltd. | Other services | 2019 |
| C&G Roofing and Insulation Services Limited | Construction | 2019 |
| C&M Security Solutions Ltd | Construction | 2025 |
| C&X Investments Limited | Administrative & support | 2023 |
| C&X Limited | Hospitality | 2022 |
| C-Systems Limited | Administrative & support | 2016 |
| C. T. Holdings Limited | Wholesale & retail | 2006 |
| C. V. Construction LLP | | 2018 |
| C.D.S. (NW) Limited | Manufacturing | 2012 |
| C.N.O Plant Hire Ltd | Construction | 2018 |
| C.T. Team Fabrics Limited | Financial services | 2023 |
| C.T.F. Contractors Limited | Construction | 2018 |
| C21 Creative Communications (EOT) Limited | Financial services | 2021 |
| C21 Creative Communications Ltd | Professional & scientific | 2006 |
| C3T Services Limited | Administrative & support | 2018 |
| C4 Carbides Holdings Ltd. | Financial services | 2021 |
| C4 Carbides Limited | Manufacturing | 1985 |
| CA Heritage Holdings Limited | Financial services | 2023 |
| CA Impact Ltd | Professional & scientific | 2025 |
| CA Lynton Bidco Limited | Financial services | 2023 |
| CA Lynton Holdco Limited | Financial services | 2023 |
| Caad Investments Ltd | Administrative & support | 2021 |
| CAB Project Management Limited | Professional & scientific | 2026 |
| Cabb UK Limited | Wholesale & retail | 2001 |
| Cablequick Limited | Administrative & support | 1989 |
| CAC Limited | Professional & scientific | 1996 |
| Cadence Recruitment Ltd | Administrative & support | 2018 |
| Cado Security Ltd | Information & communication | 2020 |
| Cadre Outdoor Limited | Arts & recreation | 2024 |
| Caer Rhun Hall Limited | Hospitality | 1949 |
| Cafe a Burger Ltd | Hospitality | 2025 |
| Cafe Seven Ltd | Hospitality | 2025 |
| Cafrica Limited | Professional & scientific | 2024 |
| Café in the Park CIC | Hospitality | 2025 |
| CAG Overseas Investments Limited | Professional & scientific | 2002 |
| Cahara Consultancy Limited | Professional & scientific | 2023 |
| CAI Engineering Solutions Limited | Administrative & support | 2023 |
| Caiila Transformative Solutions Limited | Professional & scientific | 2024 |
| Caijiana Limited | Administrative & support | 2013 |
| Cain Capital Ltd | Financial services | 2009 |
| Cainhoe Energy Ltd | Other services | 2022 |
| Caint Communications Limited | Administrative & support | 2014 |
| Cainus Ltd | Real estate | 2020 |
| Cairn Performance Limited | Professional & scientific | 2008 |
| Cake Gallery Hale Limited | Manufacturing | 2010 |
| Calavera Cafe Productions Limited | Information & communication | 2022 |
| Calbee Group (UK) Ltd | Manufacturing | 2014 |
| Calcott 23 Consulting Limited | Professional & scientific | 2023 |
| Calder Peel Partnership (London) Limited | Professional & scientific | 1997 |
| Calder Peel Partnership (Manchester) Limited | Professional & scientific | 1997 |
| Calderpeel (Holdco) Limited | Financial services | 2023 |
| Calderpeel Architects Limited | Professional & scientific | 2014 |
| Calderpeel Holdings Limited | Financial services | 2017 |
| Caldwell Brickwork Ltd | Construction | 2024 |
| Caledonia Materials Handling Limited | Administrative & support | 2015 |
| Calibra BIO Ltd | Professional & scientific | 2025 |
| California Coffee Limited | Hospitality | 2017 |
| Call Home Ltd | Real estate | 2023 |
| Call Sell Ltd | Administrative & support | 2012 |
| Callace Properties Ltd | Real estate | 2021 |
| Callisto 2112 Limited | Information & communication | 2026 |
| Callisto Finance Limited | Financial services | 2021 |
| Callwood Case Management Ltd | Health & social care | 2025 |
| Calm Minds Limited | Health & social care | 2026 |
| Calma Salons Ltd | Other services | 2024 |
| Caloenergia UK Ltd | Energy | 2022 |
| CAM Builders Limited | Construction | 2003 |
| Cam-Tech Engineering (Coventry) Limited | Manufacturing | 1998 |
| Camara Limited | Real estate | 2024 |
| Cambio Rapido Limited | Professional & scientific | 2023 |
| Cambridge Pathology and Medical Services Limited | Professional & scientific | 2025 |
| Cambur Limited | Administrative & support | 2018 |
| Camdesfil Limited | Professional & scientific | 2023 |
| Camdon Limited | Other services | 2009 |
| Camera Story Limited | Arts & recreation | 2016 |
| Cameron DIX Design Limited | Professional & scientific | 2022 |
| Cameron Neild Limited | Real estate | 2024 |
| Camino GIN Ltd | Wholesale & retail | 2020 |
| Camion Infrastructure Limited | Information & communication | 2023 |
| Campbell Harrison Limited | Financial services | 2007 |