| Crystal & Co UK Ltd | Professional & scientific | 2015 |
| Crystal Clear Holistic Health Ltd | Health & social care | 2009 |
| Crystal Clear Writing Ltd | Administrative & support | 2014 |
| Crystal Core Ltd | Construction | 2026 |
| Crystal Corner Limited | Hospitality | 2026 |
| Crystal END of Tenancy Cleaning Limited | Administrative & support | 2025 |
| Crystal Financial Solutions Limited | Financial services | 2003 |
| Crystal General Cleaning Ltd | Other services | 2019 |
| Crystal Key Investors Ltd | Real estate | 2024 |
| Crystal Logic Limited | Administrative & support | 2009 |
| Crystal Pro Cleaning Ltd | Administrative & support | 2025 |
| Crystal Products Ltd | Wholesale & retail | 2021 |
| Crystal Shisha Lounge Limited | Hospitality | 2015 |
| Crystal Solve Limited | Administrative & support | 2014 |
| Crystal Water Filters Ltd | Water & waste | 2025 |
| Crystalella Limited | Wholesale & retail | 2017 |
| Crystaline Cleaning Ltd | Administrative & support | 2015 |
| Crystallo Lava Limited | Other services | 2018 |
| CS Accounting Services Ltd | Professional & scientific | 2015 |
| CS Assets Ltd | Real estate | 2023 |
| CS Birmingham Ltd | Professional & scientific | 2025 |
| CS Bournemouth Ltd | Health & social care | 2025 |
| CS Brand Consultancy Limited | Professional & scientific | 2026 |
| CS Dental Limited | Health & social care | 2025 |
| CS Driving School Ltd | Education | 2025 |
| CS Healthcare Distribution Ltd | Manufacturing | 2022 |
| CS Luxury Motors Limited | Wholesale & retail | 2026 |
| CS Primevolt Ltd | Construction | 2026 |
| CSA Developments Limited | Professional & scientific | 2025 |
| CSC Mechanical Engineering Limited | Professional & scientific | 2018 |
| CSD GAS Limited | Construction | 2014 |
| CSG Kitchen Limited | Administrative & support | 2019 |
| CSG Quick Vend Limited | Administrative & support | 2019 |
| CSK the Beauty Ltd | Other services | 2024 |
| CSO23 Ltd | Hospitality | 2025 |
| CSP Medical Services Limited | Health & social care | 2023 |
| Cstern Holdings Ltd | Real estate | 2022 |
| CT Housewares Limited | Wholesale & retail | 2023 |
| CT Protect Ltd | Administrative & support | 2023 |
| CT Stays Ltd | Real estate | 2024 |
| CTB Group Limited | Financial services | 2025 |
| CTF Builders Ltd | Construction | 2024 |
| CTF Consultants Limited | Professional & scientific | 2026 |
| CTF Global Holdings Limited | Financial services | 2026 |
| Ctib Ltd | Education | 2023 |
| CTM Homes Limited | Real estate | 2018 |
| Ctyt Holdings Limited | Construction | 2026 |
| CU3ED Ltd | Information & communication | 2022 |
| Cuando Sailing Ltd | Extraterritorial | 2025 |
| Cube Property Investments Ltd | Real estate | 2021 |
| Cube Property Ltd | Real estate | 2016 |
| Cube Technology IT Services Limited | Information & communication | 2001 |
| Cubic Home Investment 2 Ltd | Real estate | 2020 |
| Cubic Home Investment 3 Ltd | Real estate | 2020 |
| Cubic Home Investment 4 Ltd | Real estate | 2020 |
| Cubic Home Investment 5 Ltd | Real estate | 2024 |
| Cubic Home Investment 6 Ltd | Real estate | 2025 |
| Cubic Home Investment Ltd | Real estate | 2018 |
| Cubic Homes Limited | Real estate | 2017 |
| Cubic Mews Ltd | Real estate | 2025 |
| Cubic Projects Ltd | Construction | 2018 |
| Cuckoo Lane Health Care Limited | Health & social care | 2006 |
| Cucubau Ltd | Transport & logistics | 2016 |
| CUE Point Audio Limited | Information & communication | 2017 |
| Cuffline Care Services Ltd | Health & social care | 2013 |
| Culinart Catering & Events Limited | Hospitality | 2022 |
| Cullera Capital Ltd | Construction | 2023 |
| Cultivr Ltd | Information & communication | 2026 |
| Cultura Connected CIC | Education | 2026 |
| Culture at Work Ltd | Administrative & support | 2007 |
| Cumberland Properties Management Ltd | Real estate | 2021 |
| Cura Life International Limited | Wholesale & retail | 2025 |
| Curae Solutions (UK) GP Limited | Professional & scientific | 2021 |
| Curapharm Holdings Limited | Financial services | 2024 |
| Curapharm UK Ltd | Wholesale & retail | 2018 |
| Curileum Discovery Ltd | Professional & scientific | 2013 |
| Curragh Construction Limited | Construction | 2017 |
| Curry Corner Ltd | Hospitality | 2026 |
| Curry POT (Hayes) Limited | Hospitality | 2013 |
| Curtain Call Designs Ltd | Professional & scientific | 2022 |
| Curtain Master Limited | Extraterritorial | 2024 |
| Curve Housing Limited | Real estate | 2025 |
| Curve Property Management Limited | Real estate | 2023 |
| Curzon Partners Limited | Professional & scientific | 2019 |
| Cushions by Apolonja Ltd | Manufacturing | 2025 |
| Cushte London Ltd | Hospitality | 2022 |
| Cushty Homes Ltd | Real estate | 2019 |
| Cussy Decor Limited | Construction | 2022 |
| Custodia Estate Planning Limited | Extraterritorial | 2020 |
| Custodia Financial Planning Limited | Extraterritorial | 2020 |
| Custodia Financial Services Limited | Financial services | 2012 |
| Custodian Events Limited | Construction | 2017 |
| Custom House City Limited | Construction | 2023 |
| Custom Mouldings Ltd | Other services | 2025 |
| Customblock Limited | Professional & scientific | 1998 |
| Customer 1ST Care Limited | Households | 2021 |
| Customer Needs Systems Limited | Professional & scientific | 2022 |
| Customer Technologies Ltd | Information & communication | 2017 |
| Customeyes Ltd | Manufacturing | 2017 |
| Customised by Chand Limited | Manufacturing | 2021 |