| CSH 14 Limited | Real estate | 2025 |
| CSJ Electrical Ltd | Construction | 2021 |
| CSR Travel Limited | Administrative & support | 1969 |
| CTC Marine Projects Limited | Construction | 2021 |
| CTG Metropark Limited | Hospitality | 2015 |
| Ctld Limited | Health & social care | 2013 |
| CTN Global Solutions Ltd | Professional & scientific | 2017 |
| CTR Strategy Ltd | Professional & scientific | 2023 |
| CUBA13 Ltd | Professional & scientific | 2026 |
| Cucamelon Ltd | Wholesale & retail | 2014 |
| Cucopia Services Ltd | Professional & scientific | 2023 |
| Cuddle PIE Limited | Wholesale & retail | 1999 |
| Culinary Cravings Limited | Hospitality | 2024 |
| Cullencroft Limited | Agriculture & fishing | 1972 |
| Cultura Kids Ltd | Education | 2022 |
| Cultural Journey UK Limited | Wholesale & retail | 2025 |
| Cumberland Park RTM Company Limited | Households | 2019 |
| Cumulus Design Limited | Professional & scientific | 2002 |
| Curo Business Living Property (NO.1) Limited Partnership | | 2007 |
| Currency Exchange Ltd | Financial services | 2025 |
| Custice Traders Ltd | Wholesale & retail | 2020 |
| Custom GAS Pumps Ltd | Wholesale & retail | 2011 |
| Custom LVT Flooring Limited | Construction | 2023 |
| CVH Management Limited | Professional & scientific | 2022 |
| CWB Partners Limited | Administrative & support | 2024 |
| Cwill Engineering Ltd | Professional & scientific | 2024 |
| CWN Global Ltd | Real estate | 2022 |
| Cybele Marketing Ltd | Professional & scientific | 2017 |
| Cybermaturity Limited | Information & communication | 2024 |
| Cybertrace Limited | Information & communication | 2005 |
| Cycling for Softies Limited | Extraterritorial | 2015 |
| Cyfor Enterprises Ltd | Wholesale & retail | 2024 |
| Cynetic Limited | Professional & scientific | 2003 |
| Cynopsis Solutions UK Limited | Information & communication | 2018 |
| Cyntegra Ltd | Information & communication | 2020 |
| Cyoda Limited | Information & communication | 2015 |
| D & E Property Limited | Real estate | 2011 |
| D Crozier Limited | Construction | 2012 |
| D Knox Joinery Contractors Limited | Construction | 2002 |
| D S Fenton Limited | Information & communication | 2023 |
| D T R European Sports Cars Limited | Wholesale & retail | 1996 |
| D&A Cosmetics Ltd | Wholesale & retail | 2014 |
| D&Hw Ltd | Extraterritorial | 2023 |
| D'Silva Consultancy Ltd | Information & communication | 2014 |
| D. R. Wise Ltd. | Agriculture & fishing | 2021 |
| D. Richardson & Company Limited | Agriculture & fishing | 1992 |
| D.E.S. Properties Limited | Real estate | 1953 |
| D.G. Corporate Services Limited | Professional & scientific | 1997 |
| D.H. Willis & Sons Limited | Agriculture & fishing | 2002 |
| D.M.S. Drylining Limited | Construction | 2004 |
| D.N. Designs Limited | Professional & scientific | 1993 |
| D.T. Liveries Limited | Other services | 2008 |
| D3LTA Energy Ltd | Energy | 2026 |
| DA Paolo Restaurant Limited | Hospitality | 2004 |
| Dagny Lucia Ltd | Wholesale & retail | 2026 |
| Daisy Hairstylist London Ltd | Other services | 2024 |
| Daisy Housing Community Interest Company | Hospitality | 2010 |
| Daledell Properties Limited | Real estate | 1992 |
| Daleron Ltd | Health & social care | 2014 |
| Dales Bike Centre Limited | Hospitality | 2018 |
| Dales DOC Limited | Health & social care | 2015 |
| Dales View Management Company Limited | Administrative & support | 2008 |
| Dalfor Limited | Agriculture & fishing | 2018 |
| Dalton Heights Residents Management Limited | Households | 2018 |
| Dalton Mill Limited | Real estate | 2021 |
| Dalton Mill Residential Lettings Limited | Real estate | 2025 |
| Damoa UK Ltd | Real estate | 2020 |
| Danella Limited | Professional & scientific | 2022 |
| Daniel Gabriel Limited | Other services | 2022 |
| Daniel Tomas Serrano Ltd | Arts & recreation | 2013 |
| Daniela VET Ltd | Professional & scientific | 2022 |
| Danish Centres Limited | Wholesale & retail | 2005 |
| Dannmayr Limited | Professional & scientific | 2020 |
| Danny Willett Enterprises Limited | Other services | 2008 |
| DAP Consulting Limited | Professional & scientific | 2021 |
| Dapper Mouse Films Ltd | Information & communication | 2023 |
| Dariusz Palica Holding Ltd | Administrative & support | 2019 |
| Dark Matter Studio Limited | Manufacturing | 2012 |
| Darlington (NE) Hand Car Wash Limited | Other services | 2020 |
| Darlington Roofing Contractors Limited | Construction | 2016 |
| DAS (UK) Consultancy Limited | Professional & scientific | 2005 |
| Dashwood Electrical Services Ltd | Construction | 2022 |
| DAT Film Ltd | Professional & scientific | 2020 |
| Data Images Software Solutions Ltd | Information & communication | 2009 |
| Databagel Limited | Information & communication | 2026 |
| Datai Consulting Ltd | Wholesale & retail | 2025 |
| Datazone Technologies Limited | Information & communication | 2021 |
| Datix (Holdings) Limited | Professional & scientific | 2008 |
| Datix Bidco Limited | Other services | 2018 |
| Datix Finco Limited | Other services | 2018 |
| Datix Holdco Limited | Other services | 2018 |
| Datix Limited | Information & communication | 1986 |
| Datix Midco Limited | Other services | 2018 |
| Dauntons Soar Management Limited | Real estate | 2010 |
| Dave Joyce Mechanical Services Limited | Professional & scientific | 2024 |
| Dave KAY Joinery Limited | Construction | 2002 |
| David Aldrich Designs Limited | Professional & scientific | 2009 |
| David Hampton Limited | Wholesale & retail | 2013 |
| David Lawrence Design Limited | Arts & recreation | 2012 |
| David Swinbank Limited | Agriculture & fishing | 2015 |