| Croissant Club Ltd | Arts & recreation | 2025 |
| Crophawk Ltd | Information & communication | 2025 |
| Cross Atlantic Trading Partners Ltd | Professional & scientific | 2017 |
| Crossexpert L.P. | | 2017 |
| Crosslink Media Groug Ltd | Wholesale & retail | 2025 |
| Crouton Ltd | Real estate | 2023 |
| Crowd Connect UK Ltd | Other services | 2023 |
| Crowdgate Limited | Wholesale & retail | 2025 |
| Crowes Nest Consultancy Ltd | Professional & scientific | 2025 |
| Crown Made Ltd | Financial services | 2024 |
| Crown Steel Ltd | Wholesale & retail | 2026 |
| Crown VPS Ltd | Wholesale & retail | 2023 |
| CRP Group Ltd | Professional & scientific | 2019 |
| Crunching Numbers Limited | Professional & scientific | 2008 |
| Crux Move Limited | Real estate | 2022 |
| Cruz Property Holdings Limited | Real estate | 2021 |
| Crypto Connection Ltd | Education | 2024 |
| Crypto Licence Ltd | Professional & scientific | 2025 |
| Cryptomoto Ltd | Information & communication | 2024 |
| Crystal Pictures Limited | Information & communication | 2022 |
| Crystalthink Limited | Information & communication | 2023 |
| CS Maintec Ltd | Manufacturing | 2022 |
| CS Outdoors Ltd | Wholesale & retail | 2026 |
| CSE International Ltd | Professional & scientific | 2025 |
| Ctds Consultancy Ltd | Professional & scientific | 2024 |
| CTF Investments Ltd | Financial services | 2024 |
| CTF MAC Ltd | Professional & scientific | 2026 |
| Ctpath Ltd | Health & social care | 2022 |
| Ctrl Miles Ltd | Wholesale & retail | 2025 |
| CUB & Bear Ltd | Wholesale & retail | 2024 |
| Cuban Store Ltd | Wholesale & retail | 2025 |
| Cube Nest Ltd | Real estate | 2024 |
| Cubesoft Ltd. | Information & communication | 2023 |
| Cubis - Scout Ltd | Information & communication | 2023 |
| Cuddy Lane Ltd | Extraterritorial | 2023 |
| Cullen & Allen Gifts Ltd | Wholesale & retail | 2025 |
| Cultural Paradox Limited | Education | 2025 |
| Culture Deluxe Limited | Hospitality | 2023 |
| Culture FOX Ltd | Professional & scientific | 2025 |
| Cuprumex Ltd | Wholesale & retail | 2026 |
| Cura Medical Diagnostics Ltd | Health & social care | 2023 |
| Curated Finds Ltd | Wholesale & retail | 2024 |
| Curated Keys Property Services Ltd | Households | 2025 |
| Curated Talent Group Limited | Professional & scientific | 2026 |
| Curglaff Limited | Wholesale & retail | 2025 |
| Curtis Knight Creative Limited | Professional & scientific | 2017 |
| Cushty Stays Ltd | Real estate | 2026 |
| Cusith Capital Ltd | Wholesale & retail | 2025 |
| Custom Art Solutions Ltd | Information & communication | 2023 |
| Custom Cycle Coaching Ltd | Arts & recreation | 2025 |
| Customize World Wide Ltd | Wholesale & retail | 2025 |
| Customschecks UK Limited | Wholesale & retail | 2023 |
| Cvdetect Ltd | Professional & scientific | 2021 |
| Cvexpertsuk Ltd | Other services | 2025 |
| CW Accounting Services Ltd | Professional & scientific | 2024 |
| CW Construction Ltd | Construction | 2019 |
| CWR Concepts Ltd | Professional & scientific | 2022 |
| Cwtch Silk Ltd | Manufacturing | 2026 |
| CX AI News Ltd | Information & communication | 2026 |
| Cybele Partners Ltd | Professional & scientific | 2023 |
| Cyber Coaching Ltd | Education | 2021 |
| Cyber Hogen Ltd | Information & communication | 2023 |
| Cyber Numerics Ltd | Wholesale & retail | 2024 |
| Cyber-Planet Softex Ltd. | Information & communication | 1997 |
| Cyberison Ltd | Information & communication | 2026 |
| Cyberkey IT Ltd | Information & communication | 2024 |
| Cyberwomen Groups C.I.C. | Education | 2023 |
| Cybrsupport Ltd | Information & communication | 2024 |
| CYG Limited | Wholesale & retail | 2024 |
| Cykmore Ltd | Information & communication | 2023 |
| Cylin Technologies Ltd | Wholesale & retail | 2025 |
| Cynapse Group Limited | Information & communication | 2022 |
| Cyranthos Technologies Ltd | Wholesale & retail | 2026 |
| D & a Shop Ltd | Wholesale & retail | 2023 |
| D & L Essentials UK Ltd | Wholesale & retail | 2025 |
| D Bogard Advisory Ltd | Information & communication | 2025 |
| D J K W Properties Limited | Real estate | 2025 |
| D M Lewis Properties Limited | Real estate | 2019 |
| D N MAY Limited | Other services | 2015 |
| D O Moore Holdings Limited | Financial services | 2024 |
| D R & M Farm & Investment Ltd | Other services | 2022 |
| D&B Property Group Ltd | Real estate | 2023 |
| D&K Property Management Limited | Real estate | 2025 |
| D&R Cladding & Construction Ltd | Construction | 2025 |
| D&S Bespoke Limited | Wholesale & retail | 2023 |
| D&S Property Rentals Ltd | Real estate | 2023 |
| D.J.Kennedy Transport Ltd | Transport & logistics | 2025 |
| Dabocare Health Hub Limited | Information & communication | 2025 |
| Daddy Shark Ltd | Education | 2020 |
| Dadynski Legal Services Ltd | Professional & scientific | 2024 |
| DAE Developments Limited | Real estate | 2025 |
| Daeo Ltd | Manufacturing | 2025 |
| Daffydays Ltd | Arts & recreation | 2022 |
| Daga Animation Limited | Information & communication | 2022 |
| Dahart Dynamics Ltd | Information & communication | 2024 |
| Dahort Limited | Professional & scientific | 2022 |
| Dailyvia Ltd | Wholesale & retail | 2025 |
| Daistar Global Technology Ltd | Wholesale & retail | 2025 |
| Dakshina Ltd | Hospitality | 2023 |
| Dali Technology Ltd | Information & communication | 2025 |