| CSL Murphy Investments Limited | Real estate | 2025 |
| CT Firemind Ltd | Construction | 2023 |
| CTA Contractors (Essex) Limited | Construction | 2025 |
| Ctrl ALT Admin Ltd | Administrative & support | 2026 |
| CTW Embalming Services Limited | Other services | 2017 |
| Cube Environmental Limited | Professional & scientific | 2008 |
| Cuffley & Co Ltd | Real estate | 2021 |
| Cupra Synergy Ltd | Wholesale & retail | 2025 |
| Curaim UK Limited | Construction | 2002 |
| Curatorai Ltd | Administrative & support | 2025 |
| Curly Tots Organics Ltd | Manufacturing | 2013 |
| Curlytuba Limited | Real estate | 2022 |
| Curran Contractors Ltd | Manufacturing | 2017 |
| Curran Living Ltd | Real estate | 2024 |
| Current Innovations Electrical Limited | Construction | 2024 |
| Current Projects Management Ltd | Construction | 2024 |
| Currey Consulting Limited | Professional & scientific | 2025 |
| Curve Closet Limited | Wholesale & retail | 2022 |
| Cussons Healthcare Limited | Administrative & support | 2013 |
| Custom Contractors Limited | Construction | 2015 |
| Custom Pixels Limited | Extraterritorial | 2014 |
| Custom Uniwear Designs Ltd | Wholesale & retail | 2021 |
| Custom Wheels Ltd | Transport & logistics | 2020 |
| Cutter Associates Europe Ltd | Information & communication | 2000 |
| Cuza Ltd | Health & social care | 2019 |
| Cvan Construction Ltd | Construction | 2024 |
| Cvss Limited | Administrative & support | 2005 |
| Cyan Auto Receivables Limited | Financial services | 2017 |
| Cyan Social Limited | Other services | 2021 |
| Cyber Cityz Ltd | Information & communication | 2021 |
| Cybergees Ltd | Information & communication | 2017 |
| Cyberzoneessex Ltd | Manufacturing | 2024 |
| Cycles Group Holdings Limited | Wholesale & retail | 2022 |
| Cycles Property Holdings Limited | Wholesale & retail | 2022 |
| Cycles U.K. (Holdings) Limited | Professional & scientific | 2003 |
| Cycles U.K. Limited | Wholesale & retail | 1998 |
| Cycles U.K. Rayleigh Limited | Professional & scientific | 2006 |
| Cyclone Marine Limited | Professional & scientific | 2002 |
| Czarina Construction Limited | Construction | 2019 |
| D & C Global Talent Ltd | Administrative & support | 2025 |
| D & D Farms Limited | Agriculture & fishing | 2021 |
| D & D Rail Limited | Construction | 2003 |
| D & D Storage Solutions Limited | Administrative & support | 2020 |
| D & P Home Improvement Specialists Limited | Construction | 2014 |
| D & P Services (2011) Ltd | Construction | 2012 |
| D a Smith & Sons Limited | Manufacturing | 2012 |
| D Bell Limited | Hospitality | 2006 |
| D C Glassworks Ltd | Construction | 2017 |
| D C Hurrell & Co Limited | Construction | 2004 |
| D C Painting & Decorating Limited | Construction | 2023 |
| D DOT Accounting Limited | Information & communication | 2025 |
| D Drywall Ltd | Construction | 2017 |
| D Electric Services Ltd | Energy | 2025 |
| D G Josh Limited | Construction | 2016 |
| D H Bell Ltd | Hospitality | 2015 |
| D Holland Carpentry Limited | Construction | 2015 |
| D J Beck Electrical Limited | Construction | 2007 |
| D J Building and Carpentry Specialists Limited | Construction | 2006 |
| D Keen Holdings Ltd | Real estate | 2021 |
| D Lawson Brickwork Limited | Construction | 2026 |
| D M Lindfield Limited | Health & social care | 2016 |
| D M Training Services Limited | Other services | 2018 |
| D Maguire Contracts Ltd | Administrative & support | 2023 |
| D MC Plastering Limited | Construction | 2014 |
| D N Heating Services Ltd | Construction | 2019 |
| D One Quality Ltd | Construction | 2025 |
| D P Glenister Ltd | Construction | 2007 |
| D R Enterprises Limited | Wholesale & retail | 2016 |
| D Wright Construction Ltd | Construction | 2022 |
| D&A Exteriors LLP | | 2024 |
| D&A Renovations Limited | Construction | 2023 |
| D&C Elite Property Ltd | Real estate | 2025 |
| D&Co Invest Limited | Wholesale & retail | 2020 |
| D&D Limited | Construction | 2017 |
| D&D Mobil Mechanic Ltd | Wholesale & retail | 2019 |
| D&D Patisserie Limited | Wholesale & retail | 2014 |
| D&D Perfect Building Solutions Ltd | Construction | 2020 |
| D&D Plumbing Solutions Ltd | Construction | 2026 |
| D&D Property Group Limited | Real estate | 2025 |
| D&D Property Management Limited | Other services | 2014 |
| D&D Recruitment Limited | Administrative & support | 2026 |
| D&D TRANSPORT24 Ltd | Transport & logistics | 2022 |
| D&G Investment Properties Ltd | Real estate | 2023 |
| D&G Maintenance Services Limited | Construction | 2019 |
| D&I Maintenance & Construction Ltd | Construction | 2026 |
| D&M Cars Ltd | Wholesale & retail | 2018 |
| D&M Courier Services Limited | Transport & logistics | 2022 |
| D&M Ltd | Transport & logistics | 2018 |
| D&P Gardening Ltd | Transport & logistics | 2016 |
| D&P Trans Limited | Transport & logistics | 2015 |
| D&R Barbers Limited | Other services | 2020 |
| D&R EMS Ltd | Health & social care | 2023 |
| D&R Infinite Ltd | Wholesale & retail | 2025 |
| D&S Carpenters Ltd | Construction | 2025 |
| D&T Herbal Remedies Ltd | Wholesale & retail | 2026 |
| D. a. Addo & Company Limited | Health & social care | 2013 |
| D.A.Dhaulage Ltd | Administrative & support | 2016 |
| D.F.Richards (Veneers) Limited | Manufacturing | 1972 |
| D.J.B Prestige Events Ltd | Other services | 2025 |
| D.S.M Group (U.K) Limited | Financial services | 2022 |