| Colophon Digital Projects Limited | Arts & recreation | 1999 |
| Color Box Limited | Manufacturing | 1996 |
| Colornet Limited | Information & communication | 1995 |
| Colourmatch Limited | | 1989 |
| Colsur Materials Limited | Professional & scientific | 1997 |
| Columba Europe Ltd. | Financial services | 2004 |
| COM Pipework Limited | Administrative & support | 2013 |
| Comfort Homes Ltd | Real estate | 2024 |
| Commanche Stud Limited | Agriculture & fishing | 2006 |
| Commercial Finance Solutions UK Limited | Financial services | 2006 |
| Commercial Motor Services Limited | Administrative & support | 2000 |
| Commotion Limited | Wholesale & retail | 1983 |
| Commutator Technologies Ltd. | Manufacturing | 1993 |
| Compact Communication Centre (Dartford & Gravesham) Limited | Education | 1988 |
| Compact Services Limited | Extraterritorial | 2000 |
| Compass Interiors (Europe) Limited | Wholesale & retail | 2007 |
| Compassion in Care | Health & social care | 2003 |
| Complete Construction (SE) Limited | Construction | 2007 |
| Complete Cooling Systems Limited | Manufacturing | 1984 |
| Complete Energy Group Limited | Construction | 2025 |
| Complete Payroll Services Limited | Professional & scientific | 1989 |
| Compressed Air Plant Limited | Wholesale & retail | 2005 |
| Computer Minicabs Limited | Transport & logistics | 1974 |
| Comsplan Limited | Information & communication | 2007 |
| Comtech Software Limited | Information & communication | 1995 |
| Conifer Court Residents Association Limited | Professional & scientific | 1998 |
| Conker Conservation Limited | Professional & scientific | 1999 |
| Conradi Morrison & Co LW | | 1997 |
| Constant & Durling Limited | Wholesale & retail | 1962 |
| Constantgreen Bromley Limited | Wholesale & retail | 2008 |
| Constantgreen Sevenoaks Limited | Professional & scientific | 2007 |
| Consultus Care and Nursing Ltd | Health & social care | 1983 |
| Contact Electrical (London) Ltd | Construction | 2020 |
| Continental Food Supplies (UK) Limited | Wholesale & retail | 2006 |
| Continuous Waste Management Ltd | Water & waste | 2004 |
| Contoured by Holly Academy Ltd | Education | 2025 |
| Contoured by Holly Ltd | Health & social care | 2024 |
| Contract Management Services (Medway) Limited | Professional & scientific | 2001 |
| Conyer Creek Marina LLP | | 2002 |
| Cook Capital Advisors Limited | Professional & scientific | 2011 |
| Cool Air (GB) Ltd | Wholesale & retail | 2003 |
| Cool Care (S.E.) Limited | Manufacturing | 2006 |
| Cool Spice Ltd | Hospitality | 2019 |
| Coombe Valley Transport Limited | Wholesale & retail | 1959 |
| Coote.Org Limited | Professional & scientific | 2001 |
| Copper Limited | Transport & logistics | 1999 |
| Copperhill Builders Limited | Construction | 1999 |
| Copthorn Holdings Limited | Professional & scientific | 2004 |
| Coral Consulting Limited | Information & communication | 2012 |
| Corby Building Maintenance Limited | Construction | 1996 |
| Corby Cakes Ltd | Wholesale & retail | 2020 |
| Cordelia James (Lewes) Limited | Wholesale & retail | 2016 |
| Cordelia James (RYE) Limited | Wholesale & retail | 2016 |
| Cordelia James Ltd | Wholesale & retail | 2009 |
| Cordyming Limited | Hospitality | 2003 |
| Corker Brothers Limited | Construction | 2021 |
| Cornersand Limited | Households | 1991 |
| Cornerstone Enterprises Limited | Administrative & support | 2006 |
| Cornerstone Publishing Ltd | Extraterritorial | 2009 |
| Corniche Support Services Ltd | Professional & scientific | 2015 |
| Cornwallis, Lloyd Estates Limited | Hospitality | 1979 |
| Corporate Graphics Ltd | Professional & scientific | 2007 |
| Cosa Drylining Ltd | Construction | 2014 |
| Cosgrove Drylining & Partitioning Limited | Professional & scientific | 2005 |
| Costa Insurance Services Limited | Financial services | 2006 |
| Cosy Kids Ltd | Health & social care | 2023 |
| Country First Limited | Administrative & support | 2006 |
| Country Warmth Limited | Construction | 1971 |
| Countryside 26 Limited | Construction | 2007 |
| Countryside 28 Limited | Construction | 2007 |
| Countryside Cambridge One Limited | Real estate | 2007 |
| Countryside Cambridge Two Limited | Real estate | 2007 |
| Countryside Four Limited | Construction | 2002 |
| Countryside Partnerships Limited | Financial services | 2015 |
| Countryside Properties (Commercial) Limited | Extraterritorial | 1989 |
| Countryside Properties (Housebuilding) Limited | Financial services | 2005 |
| Countryside Properties (in Partnership) Limited | Professional & scientific | 1992 |
| Countryside Properties (Joint Ventures) Limited | Financial services | 2006 |
| Countryside Properties (London & Thames Gateway) Limited | Extraterritorial | 1968 |
| Countryside Properties (Northern) Limited | Extraterritorial | 1992 |
| Countryside Properties (Southern) Limited | Professional & scientific | 1992 |
| Countryside Properties (Springhead) Limited | Construction | 2006 |
| Countryside Properties (Uberior) Limited | Construction | 2003 |
| Countryside Properties (UK) Limited | Construction | 1958 |
| Countryside Properties (WGL) Limited | Financial services | 2016 |
| Countryside Properties (WHL) Limited | Construction | 2016 |
| Countryside Properties (WPL) Limited | Construction | 2013 |
| Countryside Properties Land (One) Limited | Construction | 2005 |
| Countryside Properties Land (Two) Limited | Construction | 2005 |
| Countryside Residential Limited | Extraterritorial | 1989 |
| Countryside Thirteen Limited | Professional & scientific | 2002 |
| Countryside Timber Frame Limited | Manufacturing | 2018 |
| County AU Pairs Ltd | Extraterritorial | 2002 |
| County Border Brickwork Limited | Construction | 2006 |
| County Classics Limited | Wholesale & retail | 2004 |
| County Durham Property Centre Limited | Real estate | 2020 |
| County Garage (Sales) Limited | Wholesale & retail | 1991 |
| County Yachts Limited | Construction | 1950 |
| Court Management Associates Limited | Financial services | 2005 |
| Court Management Consultants Ltd. | Professional & scientific | 1993 |