| Commercial Real Estate Consultants Limited | Professional & scientific | 1992 |
| Comsoft Infotech PTE Ltd. | Professional & scientific | 1999 |
| Comsoft PTE Ltd. | Professional & scientific | 1999 |
| Concierge Building Services Limited | Administrative & support | 2019 |
| Confero Marketing Limited | Professional & scientific | 2005 |
| Connector Geek Limited | Information & communication | 2019 |
| Consulta GMP Ltd | Professional & scientific | 2018 |
| Consultants for Integrated Security Limited | Administrative & support | 1999 |
| Consulting & Administrative Services Ltd | Professional & scientific | 2025 |
| Consulting & Business Management, CMB, C.A. Limited | Wholesale & retail | 2005 |
| Convoke Property Limited | Real estate | 2017 |
| Cool Head Media Ltd | Professional & scientific | 2021 |
| Copperfields (Beaconsfield) Residents Company Limited | Households | 2022 |
| Cornerstone Connect Ltd | Professional & scientific | 2025 |
| Coronation Court Ltd | Construction | 2018 |
| Corporate Occupier Real Estate Consulting Limited | Real estate | 2004 |
| Cost Right Limited | Wholesale & retail | 2025 |
| Coterie Press Limited | Information & communication | 1998 |
| Cottingham Blue Chip London Limited | Wholesale & retail | 2020 |
| Countdown Property Developments Limited | Extraterritorial | 1973 |
| County Housing Solutions Ltd | Real estate | 2024 |
| Courciers Properties Limited | Real estate | 2025 |
| COX Interiors Ltd | Wholesale & retail | 2001 |
| CP Medical Services Ltd | Health & social care | 2017 |
| CPR Management Services (UK) Limited | Financial services | 2021 |
| Crane Heat Systems Ltd | Construction | 2026 |
| Crashtech Limited | Manufacturing | 2018 |
| Crawford Property Holdings UK Limited | Professional & scientific | 2019 |
| Crayfern Homes (South Coast) Limited | Construction | 2015 |
| Crayfern Limited | Construction | 2013 |
| Crayfern Sunley (Slinfold) Limited | Construction | 2019 |
| CRE8 Global Limited | Administrative & support | 2021 |
| CRE8 Licensing Limited | Wholesale & retail | 2021 |
| CRE8 Merch Limited | Wholesale & retail | 2021 |
| Createed South East C.I.C. | Education | 2022 |
| Creations Events Limited | Administrative & support | 2007 |
| Creative Incubation Ltd | Professional & scientific | 2013 |
| Creative Industries Property Summit Limited | Extraterritorial | 2024 |
| Creative Investment Capital Limited | Administrative & support | 2022 |
| Creative Lighthouse Limited | Information & communication | 2015 |
| Creatum Foundation Ltd | Health & social care | 2025 |
| Creatum Group Ltd. | Financial services | 2016 |
| Creatum Properties Ltd | Real estate | 2015 |
| Crookham Road Management Company Limited | Households | 1978 |
| Crossborder Success Limited | Administrative & support | 2018 |
| Crossbuild Limited | Construction | 1988 |
| Cruz W Consulting Ltd | Information & communication | 2022 |
| Crystal Clear Building Solutions Limited | Construction | 2011 |
| Ctrl Solutions Limited | Professional & scientific | 2013 |
| Curious Panda Ltd | Professional & scientific | 2017 |
| Curl Around Childcare Limited | Education | 2004 |
| Curly Brackets Limited | Information & communication | 2010 |
| Curvaceous Limited | Professional & scientific | 1994 |
| Curvaceous Software Limited | Information & communication | 1994 |
| Curvare Management Company Limited | Households | 2000 |
| Curve Projects Ltd | Real estate | 2009 |
| Curzon Centre | Other services | 2011 |
| Curzon College CIC | Education | 2025 |
| CVH Developments Limited | Real estate | 2014 |
| Cwaves Limited | Administrative & support | 2005 |
| Cwind Ltd | Administrative & support | 2010 |
| Cyclickal Limited | Professional & scientific | 2019 |
| Cygnera Solutions Limited | Information & communication | 2014 |
| Cygnet Nursery (Kidlington) Limited | Education | 2016 |
| Cylindo Limited | Other services | 2023 |
| Cyrus Innovations Ltd | Health & social care | 2024 |
| D B Wealth Management Limited | Financial services | 2013 |
| D Square Technology Services PVT Ltd. | Information & communication | 2019 |
| D&A Estate Management Ltd | Real estate | 2020 |
| D4D Coaching & Consultancy Ltd | Professional & scientific | 2023 |
| Daisys Gardening Services Limited | Administrative & support | 2020 |
| Daitagod Limited | Information & communication | 2025 |
| Dale-Lace Consulting Limited | Professional & scientific | 2010 |
| Dale-Lace Property Development Ltd | Real estate | 2016 |
| Dale-Lace Rental Properties Ltd | Real estate | 2016 |
| Dales Mancraft Limited | Construction | 1962 |
| Dalsara Limited | Real estate | 1988 |
| Dana Scott Integrity Consultant Ltd | Professional & scientific | 2016 |
| Danfoss Limited | Manufacturing | 1991 |
| Danfoss Power Solutions Limited | Administrative & support | 1987 |
| Daniel Gosling 32 Ltd | Construction | 2026 |
| Daniel Mendonca Property Investments Ltd | Real estate | 2022 |
| Darna Trading Limited | | 1986 |
| Darren L W Property Ltd | Information & communication | 2024 |
| Dartel Limited | Information & communication | 2009 |
| Dash of Brilliance Limited | Professional & scientific | 2014 |
| Data Protection Outsourcing Limited | Financial services | 2017 |
| Datacision Limited | Information & communication | 2005 |
| David English Studio Limited | Professional & scientific | 2025 |
| David Eyton Consulting Limited | Professional & scientific | 2024 |
| David Shuttle Limited | Wholesale & retail | 1984 |
| Davinci Design and Build Limited | Construction | 2018 |
| DB2222 Ltd | Financial services | 2025 |
| DC Inc. Limited | Administrative & support | 2012 |
| DDA Fire Limited | Public administration | 2008 |
| DE Bono House Limited | Real estate | 2026 |
| DE Novo Agents Ltd | Households | 2025 |
| Dealsourcr SL Limited | Information & communication | 2020 |
| Deans Garden Landscapes Limited | Administrative & support | 2023 |
| Deanwood Road Residents Association Limited | Other services | 1981 |