| COD Electrical Limited | Wholesale & retail | 2008 |
| Code Psie KYE Limited | Professional & scientific | 2026 |
| Codifymedia Ltd | Information & communication | 2014 |
| Coding Nomad Limited | Professional & scientific | 2019 |
| Coeliac Compass Limited | Education | 2026 |
| Coffee and Milk Tea LAB Limited | Hospitality | 2024 |
| Cogent Systems Limited | Information & communication | 2011 |
| Cogintech Limited | Professional & scientific | 2022 |
| Cognitive Advisory Limited | Professional & scientific | 2026 |
| Cognitus Consultancy Services Limited | Professional & scientific | 2023 |
| COH Sports Bidco Limited | Financial services | 2024 |
| Cohen Filippini Solicitors LLP | | 2017 |
| Coins Finance Ltd | Professional & scientific | 2019 |
| Colby River Property Management Limited | Real estate | 2016 |
| Cole-Parmer Instrument Company Limited | Wholesale & retail | 1996 |
| Cole-Parmer Limited | Manufacturing | 2007 |
| Cole-Parmer UK Bibby Acquisition Limited | Professional & scientific | 2015 |
| COLE4 Consulting Limited | Professional & scientific | 2022 |
| Colebrook Consulting Ltd | Information & communication | 2022 |
| Coles Enterprises Ltd | Administrative & support | 2013 |
| Colette Creations Ltd | Manufacturing | 2020 |
| Colin Cooke Limited | Wholesale & retail | 2005 |
| Colin Flinn Consulting Limited | Real estate | 2021 |
| Colin Mercer Consulting Limited | Professional & scientific | 2024 |
| Collabinger Ltd | Professional & scientific | 2025 |
| Collaborative Recruitment UK Ltd | Administrative & support | 2021 |
| Collectors Universe (UK) Limited | Other services | 2024 |
| Colledge Construction Limited | Wholesale & retail | 1997 |
| College Farm Management Company Limited | Real estate | 2005 |
| College Green (Crewe) Management Company Limited | Households | 2014 |
| College Green Management Company Limited | Households | 2001 |
| Colles Consultancy Services Limited | Professional & scientific | 2024 |
| Collier Littler LLP | | 2016 |
| Collings Law Limited | Professional & scientific | 2011 |
| Collins Building Solutions Ltd | Construction | 2008 |
| Collins Mchugh CSR Limited | Professional & scientific | 2020 |
| Collins Physio Ltd | Other services | 2020 |
| Collinson Software Solutions Limited | Administrative & support | 2017 |
| Colour Cube Ltd | Hospitality | 2026 |
| Colourscope Limited | Professional & scientific | 1999 |
| Columbine Restaurant Limited | Hospitality | 1997 |
| Comanche Biopharma (UK) Limited | Manufacturing | 2022 |
| Comentra Consulting Ltd | Information & communication | 2019 |
| Comfort Care MCR Limited | Health & social care | 2022 |
| Commando Force Ltd | Arts & recreation | 2019 |
| Commerce Layer Ltd. | Information & communication | 2022 |
| Commercial Brow Management Company Limited | Households | 2005 |
| Commercial Compass Limited | Professional & scientific | 2014 |
| Commercial Kitchen & Bar Ltd. | Construction | 2013 |
| Common Ground Coffee Limited | Hospitality | 2016 |
| Communicate English School Limited | Real estate | 2013 |
| Community Tatton CIC | Agriculture & fishing | 2020 |
| Community Ventures Windmill Ltd | Extraterritorial | 2019 |
| Company D Limited | Professional & scientific | 2024 |
| Compass and Sourcing Limited | Professional & scientific | 2026 |
| Compass Lifts Ltd | Construction | 2017 |
| Compass Pathfinder Holdings Limited | Financial services | 2017 |
| Compass Pathfinder Limited | Professional & scientific | 2016 |
| Compass Pathways PLC | Financial services | 2020 |
| Compassionate Care & Support (North East) Limited | Other services | 2022 |
| Compassionate Care Group Developments Limited | Real estate | 2020 |
| Compassionate Care Group Limited | Financial services | 2017 |
| Compassionate Care Group Management Limited | Professional & scientific | 2022 |
| Compassionate Care Group Services Limited | Administrative & support | 2022 |
| Compassionate Children's Care & Support Limited | Health & social care | 2023 |
| Complete Care Northwest Ltd | Other services | 2025 |
| Complete Care Training Ltd | Other services | 2025 |
| Complete Cottage Holidays Limited | Extraterritorial | 2009 |
| Complete Dairy Solutions Ltd | Manufacturing | 2026 |
| Complete Online Training Ltd | Other services | 2025 |
| Complete Optics Limited | Wholesale & retail | 2020 |
| Complete Recruitment Ltd | Other services | 2025 |
| Compliance Solutions SNS Limited | Professional & scientific | 2016 |
| Compton Garnett Consulting Limited | Administrative & support | 2014 |
| Computer Risk Management Limited | Wholesale & retail | 1993 |
| Compution Limited | Information & communication | 2023 |
| Comtest Limited | Professional & scientific | 1991 |
| Concannon Development Limited | | 1983 |
| Concept Washroom Ltd | Construction | 2015 |
| Concrete Property Investments Limited | Real estate | 2019 |
| Condado Capital UK LLP | | 2023 |
| Conduit Recruitment Limited | Administrative & support | 2002 |
| Conepate Consulting Limited | Professional & scientific | 2023 |
| Confiar Finance Limited | Financial services | 2007 |
| Confluent Solutions Limited | Professional & scientific | 2025 |
| Conifers Care Homes Ltd | Health & social care | 2005 |
| Connect Care Consultancy Ltd | Professional & scientific | 2019 |
| Connect Projects Limited | Construction | 2017 |
| Connected Logistics Solutions Ltd | Transport & logistics | 2024 |
| Connectus Wealth Management Limited | Financial services | 2020 |
| Connell Wilson Limited | Professional & scientific | 1984 |
| Connelly Consultant Group Ltd | Information & communication | 2021 |
| Connexive Limited | Administrative & support | 2020 |
| Connor Dearn MMA Ltd | Arts & recreation | 2025 |
| Connor Rees PT Limited | Arts & recreation | 2023 |
| Conpic Ltd | Professional & scientific | 2022 |
| Conquest Business Solutions Ltd | Information & communication | 2016 |
| Conquest Property Management Ltd | Real estate | 2022 |
| Conrad Gavin Landscapes Ltd | Administrative & support | 2017 |
| Conran Late Night Pharma Limited | Wholesale & retail | 2013 |