| C.P. and Sons Construction Ltd | Eastleigh | 2016 |
| C.P. Services Limited | London | 1988 |
| C.P.Dhairandbeauty Ltd | Gosport | 2025 |
| C.P.J. Field & Co. Limited | Burgess Hill | 1994 |
| C.P.R. (North West) Limited | Winwick | 2018 |
| C.R.E.E.D Organisation Ltd | Brentwood | 2025 |
| C.S Hair Studio Ltd | Hythe | 2021 |
| C.S. Hoardings & Fencing Limited | Ashford | 2008 |
| C.S. Winchcombe Funerals Limited | Devizes | 2003 |
| C.S.C. Management Limited | Inverness | 2009 |
| C.S.L.T. (Trading) Limited | | 1992 |
| C.S.R Kitchens & Bathrooms Ltd | Milton Keynes | 2022 |
| C.S.S. Environmental Limited | Chatham | 2002 |
| C.S.W. Landscapes Ltd | Northampton | 2003 |
| C.Smith & Daughter Limited | Margate | 2023 |
| C.T. Labels Limited | Wigan | 2009 |
| C.T.Butterfield and Sons Limited | Mexborough | 1964 |
| C.T.C. Health Ltd | Southport | 2018 |
| C.T.D. Enterprises Ltd | Grimsby | 2011 |
| C.T.Denton Ltd | Kidlington | 2024 |
| C.T.M. SRL Ltd | London | 2015 |
| C.T.Motors Ltd | Leicestershire | 2002 |
| C.T.S. (Midlands) Limited | Stockport | 1990 |
| C.T.S. Training & Consultancy Limited | Wisbech | 2017 |
| C.U. Nails Ltd | Nottingham | 2025 |
| C.V.East Ltd | Ipswich | 2017 |
| C.W. International Limited | Bristol | 1986 |
| C.W.Cleaning Solutions Ltd | Stoke-On-Trent | 2021 |
| C.W.Lyons & SON (Canterbury) Limited | Canterbury | 1944 |
| C.X.E.M.A Ltd | Southampton | 2015 |
| C.Y. Electrical and Cranes Company Limited | Stourbridge | 1975 |
| C1 Hair and Beauty Academy Ltd | Lichfield | 2021 |
| C13TCE Limited | Rochdale | 2025 |
| C152 Aviation & Training Ltd | Barnsley | 2024 |
| C1PHERTECH Limited | Llangefni | 2016 |
| C2 Auto Ltd | Airdrie | 2022 |
| C2 Consortium Limited | Stockport | 2014 |
| C2 Legal Limited | Harlow | 2016 |
| C2 Maintenance Limited | London | 2007 |
| C2 Promotions Limited | Bromsgrove | 1993 |
| C2B Services Ltd | Coventry | 2025 |
| C2C Adventures UK Limited | Cockermouth | 2022 |
| C2C Consultancy Limited | Poole | 2018 |
| C2C Professionals Ltd | London | 2026 |
| C2C Sales Limited | Northolt | 2015 |
| C2C Studios Ltd | London | 2024 |
| C2C-UK Group Limited | Runcorn | 2024 |
| C2IT Services Limited | Southport | 2019 |
| C2J Automotive Limited | Honiton | 2023 |
| C2M2 Investments Limited | Polesworth | 2025 |
| C2SEA Marine Ltd | Blackpool | 2024 |
| C3 Systems Consulting Ltd | Salisbury | 2009 |
| C3 Trust UK | Sheffield | 2006 |
| C360 (I.P.) Limited | Hornchurch | 2013 |
| C37 Limited | Northampton | 2005 |
| C3D Community CIC | Oxford | 2024 |
| C3I (Europe) Limited | Chester | 2004 |
| C4 Competitions Ltd | Portsmouth | 2024 |
| C4 Consultants Ltd | Hayes | 2016 |
| C4 Contracts Ltd. | London | 2012 |
| C4G Cycling CIC | Teddington | 2025 |
| C4L Laboratory Services Ltd | Burgess Hill | 2002 |
| C4PS Ltd | Hull | 2024 |
| C6 Projects Ltd | Kings Hill | 2025 |
| C60 Holdings Limited | Warwick | 2022 |
| C63 Safety Ltd | Houghton Conquest | 2015 |
| C65 (Aldwych) Limited | London | 2024 |
| C6XCHANGE Ltd | Kings Hill | 2025 |
| C7 Church | Glasgow | 2006 |
| C7 City Reach | Glasgow | 2018 |
| C7 Techsolutions Ltd | London | 2025 |
| C88 Beheer IBC Limited | Hythe | 2022 |
| C88 Holding Limited | Hythe | 2022 |
| C88 Offshore Co. Limited | Hythe | 2022 |
| C9 Beauty Salon Ltd | Bristol | 2013 |
| C9 JPF Ltd | Woodbridge | 2025 |
| CA & Co. Limited | Tarporley | 2013 |
| CA Academy Events CIC | Rowlands Gill | 2025 |
| CA Aesthetics Cosmetic Teeth Whitening London Ltd | London | 2026 |
| CA Beauty Academy Ltd | Rowlands Gill | 2019 |
| CA Boutique Ltd | Leeds | 2022 |
| CA England and Wales | Maidstone | 2009 |
| CA Fitness and Health Ltd | Leeds | 2026 |
| CA Gardening Services Ltd | Chelmsford | 2023 |
| CA Hair Limited | Waltham Cross | 2025 |
| CA Luxuries Limited | London | 2023 |
| CA Maximo Services Limited | Rotherham | 2018 |
| CA Nails Spa Ltd | London | 2022 |
| CA PHE Sang Limited | Enfield | 2024 |
| CA Specialist Services Ltd | Orpington | 2020 |
| CA Tanning and Recovery Ltd | Carlisle | 2025 |
| CA Technology Solutions Limited | Leicester | 2015 |
| CA Tree Services Limited | Boston | 2019 |
| Ca&A Limited | Colchester | 2026 |
| Ca&Ma IT Limited | Iver | 2009 |
| Ca&T Trading (UK) Limited | Sheffield | 2018 |
| CA1 Barbers Limited | Bristol | 2018 |
| CA2 Barbers Ltd | Carlisle | 2023 |
| CAA Brands UK Limited | London | 1996 |
| CAA DRY Cleaners & Laundrette Ltd | London | 2014 |