| Cat Love UK Ltd | Wholesale & retail | 2020 |
| Catalin Telecom Ltd | Information & communication | 2025 |
| CATALYST2D Group Ltd | Information & communication | 2024 |
| Catch Rate Ltd | Wholesale & retail | 2021 |
| Catchpole Contractors Ltd | Construction | 2021 |
| Catena Consultancy Limited | Health & social care | 2010 |
| Catering and Exhibition Limited | Manufacturing | 2021 |
| Catering Eshop Limited | Wholesale & retail | 2025 |
| Cathodic Corrosion Control Limited | Professional & scientific | 2013 |
| Catkin Mews Management Co Ltd | Households | 2014 |
| Catleaps GC Limited | Arts & recreation | 2011 |
| Catnis Ltd | Professional & scientific | 2015 |
| Caton Search Limited | Administrative & support | 2008 |
| Cats Been Skinned Limited | Real estate | 2023 |
| Cattle Market Catering Ltd | Hospitality | 2021 |
| Caulfield Lettings Limited | Real estate | 2025 |
| Causeway Geotechnical Limited | Construction | 2025 |
| Cavalcare Ltd | Agriculture & fishing | 2018 |
| Cavalier Haulage (Anglia) Limited | Transport & logistics | 1986 |
| Cavalry Claims Services Ltd | Administrative & support | 2019 |
| Cavara Group Ltd | Real estate | 2005 |
| Cavara Technical Services Ltd | Professional & scientific | 1994 |
| Cave J Limited | Wholesale & retail | 2007 |
| Cavendish Asset Research Ltd | Financial services | 2009 |
| Cavendish Associates Eastern Limited | Professional & scientific | 2016 |
| Cavendish Aviation UK Limited | Transport & logistics | 2005 |
| Cavenham Estates Limited | Real estate | 1999 |
| Cavenham Group Holdings Limited | Financial services | 2022 |
| Cawanda Limited | Health & social care | 2022 |
| Cazsplash Ltd | Wholesale & retail | 2017 |
| CB Installations (Halstead) Ltd | Construction | 2022 |
| CB Oddie Ltd | Hospitality | 2017 |
| CB Plumbing Limited | Construction | 2022 |
| CB Trading Essex Ltd | Hospitality | 2026 |
| CBD & BS Ltd | Construction | 2025 |
| Cbes Developments Ltd | Construction | 2020 |
| Cbesley Limited | Information & communication | 2025 |
| CBW Plant Ltd | Administrative & support | 2018 |
| CC Ceramics & Carpentry Ltd | Construction | 2025 |
| CC Construction & Groundworks Ltd | Construction | 2012 |
| CC Interim 2 Limited | Extraterritorial | 2008 |
| CC Online Sales Limited | Wholesale & retail | 2024 |
| CC Plumbing & Heating Holdings Limited | Professional & scientific | 2008 |
| CC Trading (East Anglia) Limited | Wholesale & retail | 2014 |
| CC7 Ltd | Administrative & support | 2021 |
| CCH Real Estate Services Limited | Information & communication | 2026 |
| CCH Solutions Limited | Administrative & support | 2023 |
| CCL Group (East Anglia) Limited | Information & communication | 2002 |
| CCL Lettings Limited | Real estate | 2026 |
| CCL Resources Limited | Information & communication | 2024 |
| CCL Test & Diagnostics Limited | Information & communication | 2024 |
| CCM Property Solutions Ltd | Real estate | 2024 |
| Ccom Internet Services Limited | Professional & scientific | 1998 |
| Ccom Security Services Limited | Other services | 2006 |
| CCS Colchester Cleaning Services Limited | Administrative & support | 2023 |
| CCS Transport Solution Ltd | Transport & logistics | 2021 |
| CCW R&L Limited | Construction | 2023 |
| CD Education Consultancy Limited | Education | 2016 |
| CD Office Support Services Ltd | Administrative & support | 2023 |
| Cd'Ac Ltd | Professional & scientific | 2000 |
| CDA Property Services Limited | Other services | 2012 |
| CDA Residential Properties Ltd | Real estate | 2018 |
| CDC Consultancy Limited | Financial services | 2016 |
| CDC Solutions Limited | Financial services | 2013 |
| CDL Building Contracts Limited | Construction | 2019 |
| CDM Insulations Limited | Construction | 2007 |
| Cdrp Limited | Construction | 2023 |
| CDS Care Limited | Health & social care | 2025 |
| CDV Brooke Lawrance House Limited | Construction | 2022 |
| CDV Developments Limited | Construction | 2019 |
| CDV Origin Bracknell Limited | Construction | 2022 |
| CDV Properties Limited | Households | 2018 |
| CDV Suffolk House Limited | Other services | 2022 |
| CDV Thorpe Lodge Limited | Other services | 2022 |
| CE Marketing Group Ltd | Information & communication | 2019 |
| CE Markit Limited | Professional & scientific | 2006 |
| Cecile Limited | Professional & scientific | 2012 |
| Cedar Park Management Company Limited | Households | 1998 |
| Cedars Clinic Ltd | Health & social care | 2024 |
| Cejh Limited | Real estate | 2020 |
| Celebrus Risk Limited | Financial services | 2018 |
| Cellmec Limited | Construction | 1988 |
| Celoch Cleaning Solutions Ltd | Administrative & support | 2021 |
| Celsius Hvac Limited | Construction | 2008 |
| Celtic Rose Limited | Health & social care | 2009 |
| Central C.N.C. Machinery Limited | Manufacturing | 2024 |
| Central Colchester Business Incubation Centre C.I.C. | Administrative & support | 2010 |
| Central Reservations UK Ltd | Construction | 2026 |
| Central Surveyors Limited | Other services | 2016 |
| Centralrate Property Management Limited | Households | 1989 |
| Centre for Action on Rape and Abuse | Other services | 2008 |
| Centre on Human Rights and Drug Policy Ltd | Education | 2009 |
| Centreline Services Consultants Ltd | Professional & scientific | 2013 |
| Centrum (Ipswich) Management Limited | Households | 2004 |
| Centurion Building Company Limited | Construction | 2025 |
| Centurion Community Cricket Ltd | Arts & recreation | 2023 |
| Centurion Property Services Ltd | Administrative & support | 2023 |
| Centurion Roofing Ltd | Construction | 2022 |
| Century Haven Ltd. | Administrative & support | 2024 |
| Cera Care Carers Ltd | Health & social care | 2023 |