| Claremont Events Limited | Administrative & support | 2018 |
| Clarendon Court (Torquay) Management Limited | Real estate | 2022 |
| Clarity (EOT) Limited | Financial services | 2025 |
| Clark Consult Limited | Real estate | 2011 |
| Clarus Enhanced Limited | Professional & scientific | 2026 |
| Clarus Wealth Limited | Financial services | 2012 |
| Class Accounting Ltd | Professional & scientific | 2018 |
| Classic Car Restoration and Servicing Limited | Professional & scientific | 2001 |
| Classic Furniture Ltd | Wholesale & retail | 2020 |
| Classicus Ltd | Financial services | 2015 |
| Classmate Limited | Administrative & support | 2009 |
| Classyak Ltd | Wholesale & retail | 2019 |
| Claudia Lengui Limited | Professional & scientific | 2024 |
| Claudia Nielsen Consultancy Limited | Extraterritorial | 2022 |
| Clauds Coffee House Limited | Hospitality | 2022 |
| CLC Compliance Services Limited | Professional & scientific | 2019 |
| Clean Canvas Guildford Ltd | Administrative & support | 2025 |
| Clean Canvas Surrey Ltd | Administrative & support | 2024 |
| Clean Horizons Ltd | Administrative & support | 2023 |
| Clean Revival Ltd. | Administrative & support | 2016 |
| Clean'In Time Limited | Administrative & support | 2024 |
| Cleaning Allround Ltd | Other services | 2025 |
| Cleaning Haks Ltd | Administrative & support | 2024 |
| Cleaning WOK Ltd | Administrative & support | 2026 |
| Cleanrhomes Ltd | Administrative & support | 2016 |
| Clear Sky Capital UK Limited | Financial services | 2023 |
| Clear Sky Europe LLP | | 2024 |
| Clear Sky Warehouse Limited | Real estate | 2022 |
| Clearflow 24/7 Drainage and Leak Detection Ltd | Construction | 2026 |
| Cleargif Ltd | Information & communication | 2013 |
| Clearops Ltd | Information & communication | 2025 |
| Clearpath Coaching & Consulting Ltd | Professional & scientific | 2025 |
| Clements Environmental Services Limited | Professional & scientific | 2005 |
| Cleva Technologies Limited | Information & communication | 2024 |
| Clever Acres Limited | Construction | 2025 |
| Clever Garden Tech Ltd | Information & communication | 2023 |
| Clicktomove Ltd | Construction | 2025 |
| Clifton Land Consultants Ltd | Professional & scientific | 2003 |
| Cliftons Turf Machinery Limited | Manufacturing | 1987 |
| Climb Management Services Ltd | Professional & scientific | 2015 |
| Climbing Club Kuluar Ltd | Education | 2020 |
| Clinical Skills Limited | Information & communication | 2004 |
| Clinique Lotus Ltd | Health & social care | 2022 |
| Clinisys Solutions Limited | Information & communication | 1997 |
| Clipper IT Services Limited | Information & communication | 2007 |
| Clocktower Support Limited | Financial services | 2016 |
| Clockwise Jewellery & Gems Ltd | Other services | 2025 |
| Clockwork Recruitment Ltd | Administrative & support | 2009 |
| Clokken Limited | Hospitality | 2023 |
| Close Concierge Ltd | Households | 2025 |
| Cloud Advantage Ltd | Professional & scientific | 2020 |
| Cloud Distribution Limited | Information & communication | 2009 |
| Cloud Intel Limited | Information & communication | 2026 |
| Cloud Invent Ltd | Information & communication | 2019 |
| Cloud IV Ltd | Wholesale & retail | 2026 |
| Cloud Productions Ltd | Information & communication | 2003 |
| Cloud Roofing Ltd | Construction | 2026 |
| Cloud Tools Ltd | Information & communication | 2024 |
| Clove Circle Ltd | Professional & scientific | 2024 |
| Clove Hitch Geology Ltd | Administrative & support | 2014 |
| Clovercare LP | | 2019 |
| Club Meditation Ltd | Other services | 2023 |
| Clubgreen Holdings Limited | Financial services | 2016 |
| Clubgreen Limited | Administrative & support | 2015 |
| Clubgreen Property Ltd | Administrative & support | 1991 |
| Clubhouse Support Charity Ltd | Health & social care | 2011 |
| Clubhouse Support Ltd | Health & social care | 2014 |
| Clucking Awesome Ltd | Hospitality | 2025 |
| Cmam Developments Ltd | Construction | 2020 |
| CMC Training Ltd | Administrative & support | 2007 |
| Cmcc Training Limited | Education | 2026 |
| Cmklondon Ltd | Wholesale & retail | 2020 |
| CMP Auto Collective Ltd | Wholesale & retail | 2025 |
| CMR Post Production Limited | Information & communication | 2025 |
| Cmrm Developments Limited | Construction | 2011 |
| CNJ Construction Consultants Limited | Professional & scientific | 2022 |
| Cnmara Limited | Professional & scientific | 2022 |
| Cnnct & KO Limited | Information & communication | 2026 |
| Coach IT Ltd | Other services | 2023 |
| Coaction Limited | Wholesale & retail | 2013 |
| Cobalt Accountancy Limited | Professional & scientific | 2002 |
| Cobbe Consulting Limited | Information & communication | 2018 |
| Cobham Tutors Limited | Administrative & support | 2025 |
| Cockermouth Travel Limited | Administrative & support | 2007 |
| Cocktails With Mario Ltd. | Hospitality | 2017 |
| Coco Wolf Ltd | Professional & scientific | 2013 |
| Cocos Service Limited | Health & social care | 2023 |
| Code & Click Ltd | Wholesale & retail | 2021 |
| Code Red (Holdings) Limited | Financial services | 2021 |
| Code Red Communications Limited | Professional & scientific | 2017 |
| Codeweave Limited | Information & communication | 2025 |
| Coffee & Cards Ltd | Wholesale & retail | 2021 |
| Cognimatix Consulting Ltd | Information & communication | 2023 |
| Cognipro Consultancy Group Ltd | Professional & scientific | 2023 |
| Cognissium Limited | Information & communication | 2020 |
| Cognitiva Content Services Limited | Administrative & support | 2022 |
| Cogo Studios Ltd | Information & communication | 2025 |
| Cohen Corkery (Woking) Limited | Professional & scientific | 2018 |
| Cohort Inc Ltd | Professional & scientific | 2022 |
| Coign Properties Limited | Other services | 2007 |