| Costa Enterprises Limited | Hospitality | 2025 |
| Costa Oloieri Ltd | Construction | 2019 |
| Costcutter Express Ltd | Wholesale & retail | 2015 |
| Cotuna Contractors Ltd | Construction | 2021 |
| Coulsdon Builders Surrey Ltd | Construction | 2019 |
| Court Green Education CIC | Education | 2010 |
| Court Green Investments Limited | Education | 2008 |
| Covera Housing Limited | Hospitality | 2026 |
| Cozynest Realty Ltd | Real estate | 2025 |
| CPS Ceiling Ltd | Construction | 2011 |
| CQ Builder Solution Ltd | Construction | 2026 |
| CR4 Consulting Ltd | Information & communication | 2022 |
| CR4 Estates Limited | Real estate | 2016 |
| Craig Properties Limited | Real estate | 1982 |
| Crate Solutions Limited | Transport & logistics | 2007 |
| CRE8TIVE Designs Limited | Information & communication | 2007 |
| Create Cocktails Limited | Wholesale & retail | 1999 |
| Creation KIT Ltd | Wholesale & retail | 2025 |
| Crestfield Domiciliary Care Limited | Health & social care | 2026 |
| Crew Supply Ltd | Construction | 2026 |
| Crfour Mzanzi Ltd | Wholesale & retail | 2025 |
| Cricket Green Properties Limited | Real estate | 2020 |
| Crispy Chicken HUT Ltd | Hospitality | 2020 |
| Critchley, Sharp & Tetlow Limited | Extraterritorial | 1944 |
| Crowley Lodges Ltd | Hospitality | 2021 |
| Crownline Chauffeurs Ltd | Transport & logistics | 2025 |
| Crownway UK Global Limited | Wholesale & retail | 2026 |
| Crowther & GEE Limited | Extraterritorial | 1924 |
| Croydon Fresh Bazar Limited | Wholesale & retail | 2025 |
| Croydon Gardeners Limited | Administrative & support | 2025 |
| Croydon Physiotherapy Ltd | Health & social care | 2011 |
| Croydon Scaffolding Ltd | Construction | 2008 |
| Cruising Crust Ltd | Hospitality | 2025 |
| Crystal Clover Ltd | Construction | 2003 |
| Crystal Rental Services Limited | Wholesale & retail | 2009 |
| Csws Holdings Ltd | Financial services | 2023 |
| CTA Motors Ltd | Wholesale & retail | 2022 |
| CTP Alan Limited | Extraterritorial | 1973 |
| CTP Lichfield Limited | Extraterritorial | 1938 |
| CTP Moulded Gears Limited | Extraterritorial | 1963 |
| CTP Precision Tooling Limited | Extraterritorial | 1997 |
| CTP Silleck Limited | Extraterritorial | 1945 |
| CTP White Knight Limited | Extraterritorial | 1971 |
| Custom Tuning Ltd | Manufacturing | 2016 |
| CV Parts Ltd | Wholesale & retail | 2024 |
| Cxvl UK Ltd | Wholesale & retail | 2021 |
| Cybermindset Limited | Information & communication | 2023 |
| D & Team Construction Ltd | Construction | 2015 |
| D a Ceilings ( London ) Ltd | Construction | 2019 |
| D a Ceilings ( UK ) Ltd | Construction | 2025 |
| D Khans Constructions Limited | Real estate | 2016 |
| D M & S Holdings Limited | Real estate | 2025 |
| D N H Electrical Services Ltd | Construction | 2017 |
| D N Howard Property Maintenance Ltd | Construction | 2012 |
| D Uzunov Ltd | Other services | 2018 |
| D&M (Doncea & Manole) Ltd | Transport & logistics | 2016 |
| D&M Letting Co. Ltd | Real estate | 2025 |
| D&S Professional Window Cleaning Services Ltd | Administrative & support | 2025 |
| D'Arcy Hair & Beauty Ltd | Other services | 2017 |
| D. Osbourne Construction Services Ltd | Construction | 2016 |
| D.B.T. (Motor Factors) Limited | Extraterritorial | 1967 |
| D.J.G. Exhibition Freight Services Limited | Other services | 1979 |
| D.J.G. Warehousing Limited | Professional & scientific | 1993 |
| D.L.H. Electrical Services Limited | Construction | 2006 |
| D.S.S. Construction Limited | Construction | 1993 |
| D.V.C. Services Limited | Construction | 1997 |
| Dads Engineering Ltd | Construction | 2026 |
| Daghe Trade Limited | Wholesale & retail | 2025 |
| Daily Care Support Ltd | Health & social care | 2026 |
| Daily Connect Ltd | Wholesale & retail | 2010 |
| Daily Parts Delivery Company Limited | Transport & logistics | 2023 |
| Dalton Mews Management Company Limited | Households | 2013 |
| Damirio Group Ltd | Construction | 2023 |
| DAN River Group Ltd | Agriculture & fishing | 2022 |
| Daniel Boncu Ltd | Wholesale & retail | 2019 |
| Daniel R Limited | Hospitality | 2015 |
| Danish International UK Ltd | Wholesale & retail | 2025 |
| Danmirr Capital Ltd | Other services | 2014 |
| Danmirr Secretarial Services Ltd | Administrative & support | 2012 |
| Dantes Partners (LOA) Ltd | Real estate | 2023 |
| Dantes Project Management Ltd | Professional & scientific | 2023 |
| Dantes Properties Ltd | Real estate | 2023 |
| Dare Property Maintenance Ltd | Construction | 2019 |
| Darian DS Limited | Transport & logistics | 2018 |
| Darius Ltd | Administrative & support | 2026 |
| Darren GAS Services Ltd | Construction | 2025 |
| Data Kiwi Ltd | Information & communication | 2025 |
| Datacall Limited | Extraterritorial | 1960 |
| Date Decider Ltd | Wholesale & retail | 2024 |
| Date Valley School Trust | Education | 2009 |
| Dave Freedom Limited | Other services | 2019 |
| David Musa Ministries | Other services | 2010 |
| David's Heart Empowerment and Community AID Initiative Ltd | Education | 2022 |
| Davy International Limited | Wholesale & retail | 2025 |
| Dawat Group Ltd | Manufacturing | 2024 |
| Dawkins Property Investment Ltd | Real estate | 2020 |
| Dawsonco.Uk Ltd | Real estate | 2020 |
| DBM Moffat Ltd | Construction | 2024 |
| Dcare Ltd | Education | 2019 |
| DD Standard Ltd | Construction | 2019 |