| Britten Associates Limited | Health & social care | 2013 |
| Bubl Tech Ltd | Professional & scientific | 2021 |
| C. K. Pots & Pans Limited | Wholesale & retail | 2007 |
| C434 Property Consultants Limited | Real estate | 2020 |
| Cafdem Limited | Financial services | 2025 |
| Caiged AI Limited | Information & communication | 2025 |
| Caiged C.I.C. | Other services | 2025 |
| Candour Property Services Ltd | Real estate | 2015 |
| Capricorn Laundrette Limited | Administrative & support | 2019 |
| Caritas Health Ltd | Health & social care | 2024 |
| Carol's & CDD Property Services Ltd | Real estate | 2024 |
| Casa Aria Limited | Real estate | 2024 |
| Casa Azzurri Limited | Real estate | 2018 |
| Castellina Properties Limited | Real estate | 2017 |
| Castlink Limited | Wholesale & retail | 2019 |
| Castony Ltd | Wholesale & retail | 2025 |
| Catalysd Limited | Professional & scientific | 2011 |
| Celebs Garden Ltd | Administrative & support | 2020 |
| Centurion PMI Ltd | Construction | 2015 |
| Certus Building Services Limited | Construction | 2019 |
| CFS UK Services Limited | Transport & logistics | 2021 |
| Charles Lowry Properties Limited | Real estate | 2015 |
| Chase Associates Ltd | Real estate | 2025 |
| Chelsea Photos Limited | Professional & scientific | 2026 |
| Chepyork Limited | Administrative & support | 1979 |
| Cherrystone Solutions Limited | Other services | 2021 |
| Chillington Street Limited | Real estate | 2021 |
| Chimmy Technology Services Ltd | Information & communication | 2012 |
| Chinar Business Solutions Ltd | Professional & scientific | 2013 |
| Chingford Holdings Ltd | Financial services | 2021 |
| Chisu Ltd | Construction | 2018 |
| Chloal Property Limited | Real estate | 2019 |
| Circular Trading Group Ltd | Wholesale & retail | 2026 |
| City Inn Express Limited | Hospitality | 2005 |
| Classic Nails [Ilford] Limited | Other services | 2019 |
| Claudia Bolouri Ltd | Professional & scientific | 2016 |
| Coleman Properties (Leyton) Limited | Real estate | 2009 |
| Collins Baron & Co. Limited | Construction | 2012 |
| Commongate Kitchen Ltd | Hospitality | 2024 |
| Continental Drifts Ltd | Arts & recreation | 1996 |
| Corporate Secure Limited | Administrative & support | 2022 |
| Cosme Care Limited | Other services | 2015 |
| Cottage and Castle Properties Ltd | Real estate | 2014 |
| CP & KP Ltd | Transport & logistics | 2016 |
| Cphd Limited | Professional & scientific | 2020 |
| Crama Property Limited | Construction | 2015 |
| Crama Property Management Limited | Real estate | 2026 |
| Cristowe Investments Limited | Real estate | 2016 |
| CRL Education Limited | Professional & scientific | 2018 |
| CRL Resources Limited | Financial services | 2023 |
| Crossway Autos Coachworks Ltd | Wholesale & retail | 2011 |
| Crown Court Property Management Company Limited | Households | 2021 |
| Crown Group Estates Ltd | Professional & scientific | 2025 |
| Custom Greaseproof Limited | Manufacturing | 2024 |
| CWO Consultancy Limited | Professional & scientific | 2015 |
| CXM Digital Ltd | Professional & scientific | 2023 |
| Czampas Consulting Ltd | Professional & scientific | 2021 |
| Daaks (UK) Limited | Wholesale & retail | 2007 |
| Dacorum Capital Limited | Real estate | 2023 |
| Dacorum Developments Limited | Construction | 2015 |
| Dacorum Estates Ltd | Construction | 2019 |
| Dacorum Homes Limited | Construction | 2016 |
| Dacorum Investments Ltd | Construction | 2014 |
| Dacorum Land Limited | Construction | 2016 |
| Dacorum Limited | Financial services | 2016 |
| Daily Packaging Limited | Manufacturing | 2023 |
| Dalta Cell Ltd | Administrative & support | 2016 |
| Daniel Victor Ltd | Other services | 2018 |
| Danson Lake Limited | Hospitality | 2017 |
| Danthera Limited | Financial services | 2026 |
| Darren Lewis-Harris Ltd. | Arts & recreation | 2011 |
| David Fagan Services Limited | Public administration | 2021 |
| David Jaymes Associates Limited | Arts & recreation | 1989 |
| Davis Leslie & Todd Ltd | Administrative & support | 2019 |
| DECO3000 Limited | Construction | 2013 |
| Deger London Ltd | Wholesale & retail | 2020 |
| Demetriou Family Holdings Limited | Real estate | 2015 |
| Demt UK Ltd | Financial services | 2014 |
| Denev Network Engineering Limited | Construction | 2025 |
| Desi Kulfi Faluda & Catering Ltd | Hospitality | 2023 |
| Designer Academy Ltd | Wholesale & retail | 2011 |
| Designer Metal Products Limited | Construction | 2007 |
| Designs by EK Limited | Professional & scientific | 2024 |
| Detail Audio Visual (London) Limited | Administrative & support | 2011 |
| DH & FF Limited | Real estate | 2023 |
| Diamond Architects Limited | Professional & scientific | 2010 |
| Diamond Delights Construction Limited | Wholesale & retail | 2026 |
| Diamond Delights Designers Limited | Wholesale & retail | 2026 |
| Diamond Delights Limited | Wholesale & retail | 2017 |
| Digital News Agency Ltd | Administrative & support | 2022 |
| Dillanxmusic Limited | Information & communication | 2021 |
| District MOT Limited | Hospitality | 2018 |
| Dog LEG Studios Limited | Manufacturing | 2026 |
| Done & Go Services Ltd | Agriculture & fishing | 2024 |
| Doorman (Central) Limited | | 1985 |
| Dova Homes & Constructions Ltd | Construction | 2004 |
| Dragon Engineering Consultancy Ltd | Professional & scientific | 2023 |
| Dressing Room London Limited | Wholesale & retail | 2015 |
| DRG Fitzjohn Limited | Health & social care | 2015 |
| Drivetime Autos Limited | Wholesale & retail | 2015 |