| Cardinal Lofts (Victorian Building) Limited | Administrative & support | 2015 |
| Care 1ST Limited | Health & social care | 2005 |
| Care Affect Limited | Health & social care | 2013 |
| Care Annet Ltd | Health & social care | 2019 |
| Care Assist 247 Limited | Health & social care | 2024 |
| Care Direct Essex Ltd | Health & social care | 2006 |
| Care Evolution Limited | Administrative & support | 2012 |
| Care Force Recruitment Ltd | Administrative & support | 2025 |
| Care Givers Limited | Health & social care | 2015 |
| Care Harmony Limited | Health & social care | 2016 |
| Care Haven Group Ltd | Health & social care | 2025 |
| Care Management Support Services Ltd | Health & social care | 2019 |
| Care Plus Essex Limited | Health & social care | 2005 |
| Care Robins Limited | Health & social care | 2025 |
| Care UK Care Services Limited | Administrative & support | 1991 |
| Carefirst Care Services Ltd | Administrative & support | 2013 |
| Carefirst Training Academy Ltd | Education | 2018 |
| Careful Transport 4U Ltd | Transport & logistics | 2021 |
| Careless Works Ltd | Wholesale & retail | 2026 |
| Carerose Plus Ltd | Health & social care | 2024 |
| Caretraining Essentials Limited | Education | 2025 |
| Carevia Solutions Ltd | Administrative & support | 2026 |
| Cargo Move Ltd | Transport & logistics | 2019 |
| Cargo Shift Ltd | Transport & logistics | 2025 |
| Cargo Stop International Limited | Administrative & support | 2012 |
| Cargoconnect Ltd | Transport & logistics | 2023 |
| Caribbean Starz Ltd | Wholesale & retail | 2025 |
| Carier (Braintree) Limited | Real estate | 1960 |
| Carier EGB Limited | Real estate | 2022 |
| Carier Residential Ltd | Professional & scientific | 2015 |
| Caring Hearts (Essex) Ltd | Health & social care | 2018 |
| Caring Homes (Benson) Limited | Health & social care | 2016 |
| Caring Homes (Berkshire) Limited | Health & social care | 2014 |
| Caring Homes (Broadbridge) Limited | Health & social care | 2017 |
| Caring Homes (Edinburgh) Limited | Health & social care | 2020 |
| Caring Homes (Hatfield) Limited | Health & social care | 2016 |
| Caring Homes (Malvern) Limited | Health & social care | 2015 |
| Caring Homes (Salisbury) Limited | Health & social care | 2007 |
| Caring Homes (Sandhurst) Limited | Health & social care | 2014 |
| Caring Homes (Shropshire) Limited | Health & social care | 2015 |
| Caring Homes (Standon) Limited | Health & social care | 2015 |
| Caring Homes (TFP) Group Ltd | Health & social care | 2015 |
| Caring Homes (Worthing) Limited | Health & social care | 2017 |
| Caring Homes (Wychwood) Limited | Health & social care | 2017 |
| Caring Homes Group Limited | Administrative & support | 2005 |
| Caring Homes Healthcare (Ringmer) Limited | Financial services | 2018 |
| Caring Homes Healthcare Limited | Administrative & support | 1999 |
| Carisma Bodytech Limited | Wholesale & retail | 2006 |
| Carlec Property Solutions Ltd | Construction | 2018 |
| Carleton Court Management Company Limited | Households | 1998 |
| Carlton Gilbert Construction Limited | Construction | 2010 |
| Carly Kelvin Rail Limited | Construction | 2014 |
| Carly Winer Events Ltd | Other services | 2020 |
| Carminia Consulting Limited | Administrative & support | 2024 |
| Carnaffin Limited | Real estate | 2025 |
| Carobbio Holdings Limited | Financial services | 2022 |
| Caroline Nicholls Limited | Financial services | 2023 |
| Carp Gardner Ltd | Real estate | 2019 |
| Carp Watch Official Limited | Wholesale & retail | 2026 |
| Carpe Astra Recruitment Ltd | Administrative & support | 2025 |
| Carpenter Framing Limited | Wholesale & retail | 2004 |
| Carpentier Ltd | Manufacturing | 2023 |
| Carpet Wonderland Limited | Real estate | 1983 |
| Carpfix Ltd | Agriculture & fishing | 2020 |
| Carriagehouse (UK) Limited | Financial services | 2012 |
| Carringtons Outdoor Hire Limited | Extraterritorial | 2020 |
| Carsi EN Ltd | Hospitality | 2019 |
| Carstairs Management Limited | Professional & scientific | 2013 |
| Cartec (United Kingdom) Limited | Wholesale & retail | 2013 |
| Carteks Vehicle Solutions Ltd | Wholesale & retail | 2013 |
| Carter Bros L&L Limited | Transport & logistics | 2025 |
| Carter Transport Management Ltd | Transport & logistics | 2015 |
| Cartey Plumbing & Bathrooms Ltd | Construction | 2024 |
| Carus & Sons Ltd | Wholesale & retail | 2021 |
| Carven Limited | Real estate | 2014 |
| Casa & More Ltd | Real estate | 2008 |
| Casa Ferretti Ltd | Real estate | 2023 |
| Casa MIA Construction Ltd | Construction | 2024 |
| Casa Moneta Ltd | Extraterritorial | 2016 |
| Casablanca Florists Ltd | Wholesale & retail | 2025 |
| Casanovas Recruitment Solutions Ltd | Administrative & support | 2019 |
| Case Management Works Limited | Professional & scientific | 2022 |
| Casey & Co. Bedrooms Ltd | Extraterritorial | 2025 |
| Casey & Co. Kitchens Ltd | Construction | 2020 |
| Cash £Xchange Ltd | Other services | 2011 |
| Cashmere Beauty T.E.R Ltd | Other services | 2026 |
| Cask Marque | Other services | 1998 |
| Cassandra Travel Limited | Administrative & support | 2012 |
| Casserly Foster Property Limited | Real estate | 2021 |
| Cassidy Hughes Design Limited | Professional & scientific | 2012 |
| Castle Butchery Ltd | Wholesale & retail | 2020 |
| Castle Estate Planning Ltd | Professional & scientific | 2022 |
| Castle Finance (Essex) Limited | Financial services | 2021 |
| Castle Freehold (Colchester) Limited | Households | 2026 |
| Castle Gardens (Management) Limited | Households | 2002 |
| Castle HHC Ltd | Hospitality | 2026 |
| Castle Mews (Colchester) Management Company Limited | Real estate | 2007 |
| Castle Park Theatre CIC | Extraterritorial | 2021 |
| Castlewood Holdings Limited | Professional & scientific | 1980 |
| Cat and HER Limited | Wholesale & retail | 2026 |