| Coope's Programme Management Consultancy Limited | Professional & scientific | 2007 |
| Copperlight Ltd | Wholesale & retail | 2026 |
| Coppins Management Company Limited(The) | Households | 1984 |
| Corker Group Ltd | Transport & logistics | 2024 |
| Cornwallis Estates Limited | Real estate | 2007 |
| Corser Clinic Group Limited | Health & social care | 2017 |
| Cortex Digital Group Limited | Information & communication | 2026 |
| Corvus Financial Consultants Ltd | Professional & scientific | 2014 |
| Costel Ltd | Financial services | 2024 |
| Cotters Management Company Limited | Households | 2015 |
| Coughlan Electrical Services Limited | Construction | 2015 |
| Coulman Scott Accountants Ltd | Professional & scientific | 2019 |
| Coulman Scott LLP | | 2019 |
| Countability "UK" Limited | Professional & scientific | 1996 |
| Countright Valuers Limited | Extraterritorial | 2020 |
| Cousins Contract Cleaners Limited | Administrative & support | 2020 |
| CP Estate Agents WGC Limited | Real estate | 2020 |
| CPB Auto Ltd | Wholesale & retail | 2025 |
| CPC Homes Ltd | Real estate | 2025 |
| CPJ Electrical Services Ltd | Construction | 2024 |
| CPS Cleaning Ltd | Administrative & support | 2009 |
| Cps&Co Ltd | Hospitality | 2010 |
| Craig Cody & Associates Ltd | Professional & scientific | 2021 |
| Crane & Staples (2019) Limited | Professional & scientific | 1997 |
| Crane & Staples LLP | | 2019 |
| Cranwell (Welwyn) Limited | Financial services | 2024 |
| Cream Collective Limited | Administrative & support | 2013 |
| Cream Resorts LLP | | 2012 |
| Cream Resorts Travel Limited | Administrative & support | 2014 |
| Creating Leaders for Tomorrow Ltd | Education | 2026 |
| Creative Cats Limited | Information & communication | 2014 |
| Creative Corner Homes Ltd | Real estate | 2022 |
| Creative Driveway Solutions Limited | Construction | 2026 |
| Creative Minds in Motion Ltd | Education | 2026 |
| Creative Wood Flooring Ltd | Construction | 2014 |
| Creativity Xtract Limited | Arts & recreation | 2019 |
| Creswick Pre-School Limited | Education | 2009 |
| Criptium Ltd. | Information & communication | 2018 |
| Crisp Recruitment Limited | Administrative & support | 2012 |
| Criss Painting and Decorating Ltd | Construction | 2019 |
| CRM Events Ltd | Arts & recreation | 2022 |
| Cromag Construction Ltd | Construction | 2014 |
| Cross Capital Partners Ltd | Financial services | 2025 |
| Cross-Channel Technologies Ltd | Professional & scientific | 2020 |
| Crossway Property Ltd | Households | 2021 |
| Crown Contracts Limited | Construction | 1986 |
| Crtside Limited | Education | 2025 |
| Crucial Cleaning Services Ltd | Administrative & support | 1999 |
| Crumblx AI Ltd | Professional & scientific | 2026 |
| Crystal DMS Ltd | Other services | 2005 |
| Crystal Property Investments Limited | Professional & scientific | 2007 |
| Cubetrans Ltd | Transport & logistics | 2021 |
| Culinpak Limited | Administrative & support | 2026 |
| Cultchafreak Ltd | Wholesale & retail | 2018 |
| Culturewood CIC | Hospitality | 2019 |
| Curve of Learning Limited | Education | 2025 |
| CW Digitech Ltd | Information & communication | 2005 |
| Cyber Agents Ltd | Manufacturing | 2022 |
| Cybertekshift Ltd | Information & communication | 2024 |
| Cypress Property Management Limited | Real estate | 2016 |
| D & B Homes Limited | Real estate | 2018 |
| D Cook Security Consultants Limited | Administrative & support | 2013 |
| D Crashaw Limited | Construction | 2017 |
| D E&P Limited | Construction | 2024 |
| D J M Maintenance Ltd | Construction | 2025 |
| D Jones Utilities Limited | Energy | 2024 |
| D&S Consultants Limited | Professional & scientific | 2025 |
| D2CARE Limited | Health & social care | 2023 |
| Dale Associates Construction Limited | Construction | 2007 |
| Damien Poulter Designs Ltd | Professional & scientific | 2015 |
| Danmai Ltd | Wholesale & retail | 2025 |
| Dannys Disposal Ltd | Water & waste | 2025 |
| Dapp Technologies Ltd | Professional & scientific | 2020 |
| Dapur Dining (UK) Limited | Hospitality | 2018 |
| Daraja Trading Ltd | Administrative & support | 2019 |
| Dark Matter LAB Ltd | Real estate | 2026 |
| Daruma Projects Limited | Information & communication | 2023 |
| Data Enhancement Solutions Ltd | Information & communication | 2020 |
| Data FIX Limited | Construction | 2024 |
| Datchworth Heating Ltd | Construction | 2026 |
| David Morgan Ltd | Transport & logistics | 2010 |
| David Watkins Homes Limited | Real estate | 2000 |
| Davidson-Roberts Holdings Ltd | Financial services | 2018 |
| Davidson-Roberts Limited | Education | 2006 |
| Ddcr Holdings Limited | Other services | 2025 |
| DE Waal Labs Ltd | Information & communication | 2026 |
| Deadpixel Digital Ltd | Professional & scientific | 2022 |
| Deal BOY Ltd | Professional & scientific | 2020 |
| Dean Mcshane Contracting Limited | Information & communication | 2011 |
| Dearcu Hairdressing and Beauty Salon Ltd | Other services | 2024 |
| Deeanday Properties Ltd | Real estate | 2020 |
| Deed Group Ltd. | Professional & scientific | 2010 |
| Definitely Cake Limited | Extraterritorial | 2016 |
| Defu LI Limited | Wholesale & retail | 2026 |
| Delmas Consulting Limited | Administrative & support | 2014 |
| Dembol Transport and Cleaning Ltd | Transport & logistics | 2018 |
| Demianyk Lobb Limited | Professional & scientific | 2013 |
| Demolight Limited | Information & communication | 2015 |
| Demolition Contracting UK Limited | Construction | 2013 |
| Demtec Limited | Extraterritorial | 2021 |