| COREBOX2 Ltd | Information & communication | 2023 |
| Corn Close (Stone) Residents Association Limited | Households | 1990 |
| Cornmill Mews Management Company Limited | Households | 2016 |
| Coronation Mews Management Company Limited | Households | 2003 |
| Coruscant Limited | Information & communication | 2008 |
| Cosmic Coatings Ltd | Construction | 2025 |
| Cosmo Consulting Limited | Professional & scientific | 2016 |
| Cosmos IQ Limited | Information & communication | 2019 |
| Costume Styling Ltd | Arts & recreation | 2014 |
| Cotmas Limited | Information & communication | 2019 |
| Cotsmoor Management Company Limited | Households | 1994 |
| Cotswold Electroworks Limited | Manufacturing | 2025 |
| Cotswolds Change Services Limited | Professional & scientific | 2023 |
| Cottesmore RTM Limited | Households | 2012 |
| Coulure Limited | Wholesale & retail | 2025 |
| Countryside Gardens Ltd | Administrative & support | 2021 |
| Countryside Pubs Ltd | Hospitality | 2015 |
| Countrywide Estate Agents (South) Limited | Professional & scientific | 1988 |
| Countrywide Estate Agents Limited | Real estate | 1964 |
| Countrywide Group Holdings Limited | Financial services | 1984 |
| Countrywide Group Limited | Financial services | 2003 |
| Countrywide Limited | Professional & scientific | 2012 |
| Countrywide Property Auctions Limited | Professional & scientific | 1980 |
| Countrywide Residential Lettings Limited | Real estate | 1994 |
| Countrywide Residential Lettings Nominees Limited | Extraterritorial | 2019 |
| County View Commercial Cleaning Services Ltd | Administrative & support | 2010 |
| Court Place Management Company Limited | Households | 1988 |
| Cousins Construction Consultants Ltd | Professional & scientific | 2020 |
| Cousins Property Management Limited | Households | 2025 |
| Coutts Controls Ltd | Other services | 2022 |
| Cove Enterprise Ltd | Wholesale & retail | 2013 |
| Covolve Limited | Professional & scientific | 2016 |
| Cowley Holmes Associates Limited | Financial services | 1994 |
| Cox-Smith Consultants Limited | Professional & scientific | 1996 |
| Coyle Accountants Limited | Professional & scientific | 2014 |
| CPD Scaffolder Limited | Construction | 2020 |
| CPY Excavations Limited | Construction | 2013 |
| Cqvolution Ltd | Professional & scientific | 2021 |
| CR Go-To-Market Advisors Limited | Professional & scientific | 2026 |
| Crafted Handrails Limited | Manufacturing | 2003 |
| Craig Lambert Associates Limited | Professional & scientific | 2001 |
| Craig Ross Limited | Administrative & support | 2015 |
| Craig Stephen Mortgages Limited | Financial services | 2022 |
| Cranfield Gardens Management Company Limited | Households | 2009 |
| Crawford Taverns Ltd | Hospitality | 2024 |
| Creata Solution Limited | Professional & scientific | 2001 |
| Create Dialogue Limited | Education | 2024 |
| Creator's Workshop Limited | Professional & scientific | 2023 |
| Creature Records Ltd | Arts & recreation | 2024 |
| Credential Vault Ltd | Other services | 2023 |
| Crescere Consulting Ltd | Professional & scientific | 2025 |
| Cricketers Mews Ltd | Households | 2007 |
| Critical P3M Limited | Professional & scientific | 2016 |
| Croft Design Studio Limited | Arts & recreation | 2018 |
| Croft Engineering Advisory Limited | Professional & scientific | 2025 |
| Crofts Estate Agents Limited | Real estate | 2005 |
| Cronetek Ltd | Professional & scientific | 2009 |
| Crowborough Management Co. Limited | Real estate | 1996 |
| Crown Construction (Home Counties) Limited | Construction | 2019 |
| Crown Network Solutions Limited | Information & communication | 2010 |
| Croxden Close Limited | Households | 2017 |
| Cryosharp Limited | Information & communication | 2025 |
| Crystal Advisory Limited | Extraterritorial | 2012 |
| CS Hairshine Limited | Other services | 2023 |
| CS Installations & Projects Ltd | Construction | 2022 |
| CT Aviation Company Limited | Manufacturing | 2022 |
| CT Global Services Limited | Health & social care | 2022 |
| CTF Photography Limited | Professional & scientific | 2018 |
| Culdan Sports Ltd | Wholesale & retail | 2018 |
| Culley Properties Limited | Real estate | 2022 |
| Cultivate (UK) Ltd | Professional & scientific | 2009 |
| Cultivate Learning Ltd | Education | 2025 |
| Cumulus Sourcing Limited | Professional & scientific | 2010 |
| Cuppy Cares CIC | Education | 2024 |
| Curtis Estates LLP | | 2017 |
| Curva Spine Ltd | Arts & recreation | 2020 |
| CWJ Limited | Information & communication | 2015 |
| Cxmi Limited | Information & communication | 2024 |
| Cyberdrove Limited | Information & communication | 2022 |
| Cybersure Limited | Information & communication | 2015 |
| Cybia Ltd | Professional & scientific | 2011 |
| D & P Molloy Paving Ltd | Construction | 2011 |
| D Aston Roofing Ltd | Construction | 2022 |
| D L Miller Services Ltd | Construction | 2023 |
| D M J Roberts Transport Ltd | Transport & logistics | 2023 |
| D M Pretzels Limited | Wholesale & retail | 2007 |
| D Mcelholm Consultancy Services Limited | Professional & scientific | 2025 |
| D R Ventilation Limited | Construction | 2003 |
| D R Ventilation Services Ltd | Construction | 2019 |
| D Three Limited | Information & communication | 2004 |
| D V Capital Limited | Real estate | 2017 |
| D White Building Limited | Construction | 2024 |
| D&R Taxis Plus Ltd | Transport & logistics | 2017 |
| D-Mec Services Limited | Construction | 2000 |
| D. & I. Transfreight Limited | | 1984 |
| D. I. Z. Limited | Other services | 2002 |
| D.A.N Communications Limited | Information & communication | 2016 |
| D.G. Cricket Limited | Arts & recreation | 2006 |
| D.L.A. Home Services Ltd | Construction | 2019 |
| Daacr Ltd | Hospitality | 2025 |