| CS Medical Consulting Ltd | Health & social care | 2024 |
| CS Property Specialists Ltd | Construction | 2025 |
| Cscm Group Holdings Limited | Financial services | 2023 |
| CSD Construction Services Ltd | Construction | 2018 |
| CSD Fire Solutions Ltd | Construction | 2021 |
| CSE Installations Limited | Construction | 2018 |
| CSJ Plumbing & Heating Ltd | Construction | 2023 |
| CT Home Clearance Limited | Water & waste | 2023 |
| CT Homes Investments Ltd | Financial services | 2023 |
| CT Laminators Ltd | Manufacturing | 2025 |
| CTD Kitchens Ltd | Manufacturing | 2023 |
| Ctrl Home Limited | Wholesale & retail | 2020 |
| CU Recruitment Ltd | Administrative & support | 2022 |
| Cubra Construction Ltd | Construction | 2022 |
| CUE Shop Limited | Manufacturing | 2017 |
| Cuenca Medical Services Limited | Health & social care | 2019 |
| Cuex Ltd | Manufacturing | 2024 |
| Cullen's Property Rental Limited | Real estate | 2020 |
| Cumberland Construction Southern Limited | Construction | 2016 |
| Cummins and Pope Limited | Construction | 1982 |
| Cunningpad Ltd | Financial services | 2022 |
| Cura Domiciliary Services Ltd | Health & social care | 2025 |
| Curationtech Alma Road Ltd | Real estate | 2022 |
| Curationtech Aurum Ltd | Real estate | 2020 |
| Curationtech Fareham Ltd | Construction | 2022 |
| Curationtech Holdings Ltd | Construction | 2020 |
| Curationtech Properties Ltd | Real estate | 2023 |
| Curdridge MOT Centre Limited | Wholesale & retail | 2024 |
| Curhams Limited | Professional & scientific | 2014 |
| Curious Corner Ltd | Wholesale & retail | 2025 |
| Curious Lighthouse Learning Consultancy Ltd | Education | 2016 |
| Custodia Fire Protection & Security Services Ltd | Construction | 2024 |
| Custom Cables Ltd | Wholesale & retail | 2025 |
| Cutlers Trading Ltd | Administrative & support | 2024 |
| CWX Holdings Ltd | Construction | 2026 |
| CXP Enterprises Ltd | Hospitality | 2023 |
| Cyan Solutions Limited | Information & communication | 2004 |
| Cybserve Ltd | Information & communication | 2025 |
| Cycas Investments Limited | Real estate | 2025 |
| Cyme Developments Limited | Construction | 2016 |
| Cyntel Ltd | Information & communication | 2019 |
| D & G Safety Services Ltd | Transport & logistics | 2023 |
| D B Bricklaying Services Limited | Construction | 2020 |
| D B C Building Services Limited | Construction | 2018 |
| D Berry Holdings Ltd | Financial services | 2020 |
| D Bolton Builders Ltd | Construction | 2024 |
| D Dawes Ltd | Real estate | 2020 |
| D F Healthcare Limited | Health & social care | 2015 |
| D G H Rail Limited | Construction | 2018 |
| D G Landscaping Limited | Administrative & support | 2019 |
| D Hill Services Limited | Transport & logistics | 2001 |
| D J Evans Holdings Ltd | Financial services | 2016 |
| D J F Carpentry Services Limited | Construction | 2016 |
| D J M Installations Ltd | Construction | 2023 |
| D J MEW Roofing Ltd | Construction | 2022 |
| D J R General Services Limited | Extraterritorial | 2017 |
| D K Electrical Projects Limited | Construction | 2014 |
| D Knott Electrical and Property Development Ltd. | Construction | 2018 |
| D L F GAS Limited | Construction | 2014 |
| D M B Flat Roofing & Building Services Ltd | Construction | 2009 |
| D M L Electrical & Property Services Limited | Construction | 2011 |
| D M L Tech Limited | Construction | 2018 |
| D M Phillips Plumbing & Heating Limited | Construction | 2012 |
| D P H Groundworks Limited | Construction | 2009 |
| D P Technology Services Ltd | Information & communication | 2004 |
| D R Lifting Limited | Construction | 2018 |
| D R Rail & Civils Ltd | Construction | 2023 |
| D S Enterprises Southern Limited | Real estate | 2019 |
| D Savage Home Improvements Ltd | Construction | 2021 |
| D Scott & Sons (Hampshire) Ltd | Construction | 2014 |
| D T W Roofing Limited | Construction | 2017 |
| D W Solutions Ltd | Administrative & support | 2016 |
| D&H Scaffolding Ltd | Construction | 2025 |
| D&R Wilds Ltd | Real estate | 2026 |
| D-Wellness Limited | Health & social care | 2026 |
| D. O. Productions Limited | Arts & recreation | 2011 |
| D.A. & J.J. Colliver Limited | Construction | 1980 |
| D.A. Harris Estates Ltd | Real estate | 2022 |
| D.J. Connolly Electrical Ltd | Construction | 2017 |
| D.J. Lifting Ltd | Construction | 2017 |
| D.P Rental Properties LLP | | 2024 |
| D.P. Properties (Southern) Limited | Construction | 2011 |
| D351GN Limited | Professional & scientific | 2022 |
| Dabarr Limited | Administrative & support | 2025 |
| Dach Business Development Ltd | Information & communication | 2024 |
| Dadcars Limited | Information & communication | 2025 |
| Dadth Ltd | Manufacturing | 2024 |
| Daedalus Cove Investments Ltd | Professional & scientific | 2021 |
| Dafe Properties Ltd | Real estate | 2018 |
| Daga Rail Services Ltd | Transport & logistics | 2023 |
| Dagnell Gold Limited | Wholesale & retail | 2013 |
| Daiva's Academy Ltd | Other services | 2021 |
| DAK Contractors Ltd | Construction | 2019 |
| Dalewood Holdings Limited | Financial services | 2016 |
| Dalewood Investments Limited | Administrative & support | 2021 |
| Dalewood Overseas Limited | Real estate | 2023 |
| Daley Fitness Ltd | Extraterritorial | 2014 |
| Daley Training Ltd | Extraterritorial | 2013 |
| Daleyfitness Weekenders Ltd | Administrative & support | 2013 |
| Dalliance Limited | Administrative & support | 2016 |