| Clarke Path Estates Ltd | Real estate | 2025 |
| Classic Sourcing Ltd | Wholesale & retail | 2019 |
| Classyk Digital Ltd | Information & communication | 2025 |
| Claycart Electrical Ltd | Construction | 2024 |
| Clayton Wigan Estates Limited | Other services | 2024 |
| CLB Consulting Ltd | Professional & scientific | 2019 |
| Clbx Solutions Ltd | Wholesale & retail | 2024 |
| Clean Books Software Ltd | Information & communication | 2022 |
| Clean Gene UKK Ltd | Administrative & support | 2025 |
| Cleanix Solutions CIC | Administrative & support | 2026 |
| Cleansheets Pride Ltd | Wholesale & retail | 2024 |
| Cleanuk Services Ltd | Administrative & support | 2025 |
| Clear Energy Services Ltd | Professional & scientific | 2026 |
| Clear Waste RIP Outs Ltd | Water & waste | 2026 |
| Clearance Shed Limited | Wholesale & retail | 2018 |
| Clearance Trade Centre Limited | Wholesale & retail | 2013 |
| Clearaway Group Ltd | Water & waste | 2025 |
| Clearbox Limited | Extraterritorial | 1904 |
| Clearhold Property Ltd | Real estate | 2026 |
| Clearpath GP Services Ltd | Health & social care | 2026 |
| Clearstay Management Ltd | Administrative & support | 2025 |
| Cleartrial Ltd | Information & communication | 2026 |
| Cleethorpes Estates Ltd | Real estate | 2011 |
| Cleethorpes Estates NO.2 Ltd | Extraterritorial | 2015 |
| Cleveland Birkenhead Limited | Real estate | 2019 |
| Click 4 Bargain Ltd | Wholesale & retail | 2013 |
| Click 4 Buy Ltd | Wholesale & retail | 2019 |
| Click Clique Limited | Professional & scientific | 2019 |
| Click Industries UK Ltd | Wholesale & retail | 2024 |
| Click Kiosk Ltd | Information & communication | 2024 |
| Clickasave Ltd | Wholesale & retail | 2023 |
| Clicky Auto Ltd | Wholesale & retail | 2022 |
| Client Assist Limited | Financial services | 2020 |
| Cliff Grange Estates Ltd | Real estate | 2025 |
| Clifftop Estates Limited | Professional & scientific | 2005 |
| Clifton Waterside Ltd | Construction | 2020 |
| Clifwood Holdings Ltd | Real estate | 2023 |
| Climac Holdings Limited | Professional & scientific | 2024 |
| Climate Creative Ltd | Information & communication | 2020 |
| Climbing Trees Online Marketing Ltd | Professional & scientific | 2010 |
| Clinic First Limited | Real estate | 2026 |
| Clinical Assessments Limited | Other services | 2016 |
| Clinical Negligence Experts Ltd | Professional & scientific | 2025 |
| Clints Fest Ltd | Arts & recreation | 2025 |
| Clka Services Limited | Professional & scientific | 2017 |
| Cllas Building & Maintenance Ltd | Construction | 2024 |
| Clobster Manchester Ltd | Hospitality | 2025 |
| Cloisters Trustees Limited | Administrative & support | 2018 |
| Closer Homes Limited | Real estate | 2013 |
| Cloud Bookkeeping Services Ltd | Professional & scientific | 2015 |
| Cloud Native Services Ltd | Information & communication | 2019 |
| CLOUD53 Ltd | Information & communication | 2015 |
| Cloudbricks Ltd | Real estate | 2025 |
| Cloudburster Ltd | Extraterritorial | 2013 |
| Cloudify Store Limited | Wholesale & retail | 2026 |
| Clover CLO Ltd | Wholesale & retail | 2026 |
| Clowes Bureaucracy Experts Ltd | Professional & scientific | 2017 |
| Clowes Ltd | Wholesale & retail | 2025 |
| CLP Consultancy Limited | Professional & scientific | 2022 |
| Club Atlético Manchester Ltd | Arts & recreation | 2025 |
| Club Power Elite Limited | Other services | 2018 |
| Cluny Mews Developments Commercial Limited | Construction | 2022 |
| Cluny Mews Developments Limited | Construction | 2021 |
| Cluny Mews Management Company Limited | Households | 2022 |
| Cluster Properties Ltd | Real estate | 2019 |
| Clyde House Limited | Health & social care | 2005 |
| Clyde Union DB Limited | Manufacturing | 1937 |
| CM Balaban Ltd | Transport & logistics | 2024 |
| CM International Trading Ltd | Information & communication | 2018 |
| Cmas Rents Limited | Real estate | 2009 |
| CMC Legal Services Limited | Professional & scientific | 2025 |
| CMC Spaces Ltd | Hospitality | 2025 |
| Cmcb Consulting Limited | Professional & scientific | 2026 |
| CME Management Properties Ltd | Construction | 2022 |
| Cnba Studios Ltd | Other services | 2025 |
| CNC Consult Ltd | Professional & scientific | 2025 |
| CNF Electrical Limited | Construction | 2024 |
| Co-Fm Ltd | Administrative & support | 2020 |
| Co-Low Assets Ltd | Real estate | 2023 |
| Coach Reach Ltd | Professional & scientific | 2019 |
| Coach'D Group Limited | Health & social care | 2025 |
| Coaching by PAV ZUK Ltd | Education | 2026 |
| Coaching Club Consulting Ltd | Professional & scientific | 2018 |
| Coalfield Estates Holdings Limited | Other services | 2025 |
| Coastal Dreams Limited | Other services | 2018 |
| Cobac Holdings Limited | Professional & scientific | 1995 |
| Cobac Holdings One Limited | Professional & scientific | 2000 |
| Cobac Holdings Two Limited | Extraterritorial | 2010 |
| Cobalt Investments (Newcastle) Ltd | Real estate | 2026 |
| Cobournerailway Ltd | Construction | 2025 |
| Cobymoll Cottages Ltd | Real estate | 2022 |
| Cochavim Estates Limited | Other services | 2021 |
| Coco Dolce Limited | Professional & scientific | 2019 |
| Coconut Leisure Limited | Real estate | 2025 |
| Cocoon Estate Limited | Real estate | 2025 |
| Code LAB Services Ltd | Wholesale & retail | 2025 |
| Code Marking Limited | Financial services | 2016 |
| Codingpie Ltd | Information & communication | 2025 |
| Coffee Moffee Ltd | Wholesale & retail | 2023 |
| Coffee Rules Limited | Hospitality | 2023 |