| CSQ Management Ltd | Professional & scientific | 2021 |
| CSS Roof Tiling Specialists Ltd | Construction | 2021 |
| CST Logistics Ltd | Transport & logistics | 2025 |
| CTP Builders Limited | Construction | 2014 |
| CTZ Electrical Contractors Ltd | Construction | 2016 |
| Cucu Creative Limited | Information & communication | 2023 |
| Cuddle Club Ltd | Wholesale & retail | 2024 |
| Cult Culture Ltd | Manufacturing | 2016 |
| Cumbria Living Ltd | Real estate | 2025 |
| Cumulative Capital Ltd | Real estate | 2020 |
| Cunningham Let's Ltd | Real estate | 2026 |
| Cupidon Ltd | Professional & scientific | 2021 |
| Cure Talent Limited | Administrative & support | 2022 |
| Curnon Consulting Ltd | Professional & scientific | 2018 |
| Curtis Creative Limited | Information & communication | 2012 |
| Curtis-X Ltd | Information & communication | 2025 |
| Custodian People Limited | Administrative & support | 2018 |
| Custom Card Services International Limited | Manufacturing | 1992 |
| Custom Stitch and Print Ltd | Manufacturing | 2021 |
| Custom-Fit Kitchens Ltd | Construction | 2014 |
| Customer Engagement Technologies Limited | Professional & scientific | 2016 |
| CUT & Trim Ltd | Other services | 2026 |
| CUT Above Productions Limited | Information & communication | 2017 |
| Cvconstruct Ltd | Construction | 2025 |
| CVM People Limited | Professional & scientific | 2013 |
| CVS IT Solutions Limited | Information & communication | 2016 |
| CW Aviation Services Limited | Professional & scientific | 2017 |
| CW Rovers Limited | Wholesale & retail | 2014 |
| CWR Building Services Limited | Construction | 2014 |
| CX Technical Services Ltd | Professional & scientific | 2018 |
| CY Homes Ltd | Construction | 2015 |
| Cyber Foundry Ltd | Other services | 2017 |
| Cyber Security Support Ltd | Information & communication | 2025 |
| Cyberdive Limited | Information & communication | 2016 |
| Cybertekk Ltd | Information & communication | 2022 |
| Cygnature Homes Ltd | Construction | 2020 |
| Cykool Limited | Professional & scientific | 2009 |
| Cytec Limited | Administrative & support | 1998 |
| CZ Drones Ltd | Professional & scientific | 2023 |
| D & G Solution Management Ltd | Information & communication | 2020 |
| D & G Tennis Ltd | Hospitality | 2022 |
| D & M Build Ltd | Construction | 2019 |
| D & N Collections Ltd | Construction | 2026 |
| D & SP Limited | Professional & scientific | 2005 |
| D B S Brand Factors Ltd | Extraterritorial | 2001 |
| D Lincoln Screeding Ltd | Construction | 2020 |
| D M J Sawyer Limited | Information & communication | 2010 |
| D M Page Plumbing & Heating Limited | Construction | 2008 |
| D N Dental Limited | Health & social care | 2011 |
| D Phippard Interpreting Ltd | Professional & scientific | 2011 |
| D R Guppy Limited | Health & social care | 2011 |
| D Simon Ortho Surgery Limited | Health & social care | 2010 |
| D&Dot Ltd | Wholesale & retail | 2025 |
| D&M Nexus Inc. Ltd | Professional & scientific | 2025 |
| D&V Finishing Ltd | Construction | 2021 |
| D.A.S Construct Ltd | Construction | 2025 |
| D.Cs Contracts Limited | Information & communication | 2005 |
| D.E.Stevens Limited | Administrative & support | 2017 |
| D.R.G. & Transport Ltd | Transport & logistics | 2022 |
| D.T. Lisa Court Limited | Households | 1975 |
| D2C Analytics Ltd | Information & communication | 2025 |
| D5 Management Limited | Professional & scientific | 2012 |
| DA Cunha Advisory Limited | Administrative & support | 2017 |
| DA Mariu' Basingstoke Ltd | Hospitality | 2025 |
| DA Mariu' Ltd | Hospitality | 2023 |
| Dadams Investments Ltd | Administrative & support | 2020 |
| Daedalus Conservation Limited | Construction | 2011 |
| Dalaman Properties Limited | Real estate | 2018 |
| Dalgety Pension Trust Limited | Financial services | 1956 |
| Dalithammy Ltd | Health & social care | 2026 |
| Dalln Limited | Construction | 2013 |
| Dalmec Limited | Manufacturing | 1990 |
| Daluso Ltd | Real estate | 2023 |
| Damata. Limited | Health & social care | 2023 |
| Damvuri Consulting Limited | Professional & scientific | 2019 |
| DAN Marsh Films Ltd | Professional & scientific | 2021 |
| DAN TES DAN Ltd | Transport & logistics | 2018 |
| Dance in the Rain Limited | Professional & scientific | 2010 |
| Dance Inc Limited | Arts & recreation | 2005 |
| Dandelions Community Pre-School | Education | 2004 |
| Danek Transport Limited | Transport & logistics | 2014 |
| Daneri Security Solutions Ltd | Information & communication | 2024 |
| Daneshill Court (Residents) Limited | Households | 2016 |
| Daniel David James Limited | Construction | 2013 |
| Daniel Freya Events Limited | Administrative & support | 2007 |
| Daniel Oliver Plumbing and Heating Ltd | Construction | 2024 |
| Danmag 0812 Ltd | Transport & logistics | 2019 |
| Danrom Ltd | Transport & logistics | 2014 |
| Danruss Transport Ltd | Transport & logistics | 2021 |
| Danycos Transport Ltd | Transport & logistics | 2017 |
| Dara Cleaning Limited | Administrative & support | 2016 |
| Darcy Morgan Ltd | Wholesale & retail | 2025 |
| Dare PA Ltd | Administrative & support | 2018 |
| Dariusz M Consultancy Ltd | Professional & scientific | 2022 |
| Dark City Games Ltd | Manufacturing | 2022 |
| Darklabs Cyber Ltd | Information & communication | 2025 |
| Darren a Smith Financial Services Ltd | Financial services | 2009 |
| Darren J. Benjamin Music Ltd | Arts & recreation | 2015 |
| Darsen MAY Ltd | Wholesale & retail | 2021 |
| Darshini on Wheels Ltd | Hospitality | 2024 |