| Conington Park Farms Limited | Agriculture & fishing | 2018 |
| Conkers Trading Ltd | Other services | 2018 |
| Connaught Media and PR Limited | Extraterritorial | 2012 |
| Connect Business Networking Limited | Information & communication | 2017 |
| Connect GOV Ltd | Hospitality | 2023 |
| Connect Haulage Ltd | Transport & logistics | 2020 |
| Connected to Homes Ltd | Manufacturing | 2018 |
| Connected UK Care Limited | Health & social care | 2013 |
| Connecting EYE CIC | Other services | 2024 |
| Connor's Autos Ltd | Wholesale & retail | 2019 |
| Conquered Limited | Health & social care | 2018 |
| Conquest Schools Ltd | Education | 2024 |
| Conservation Careers Ltd | Administrative & support | 2014 |
| Consilium Wealth Limited | Financial services | 2015 |
| Consolidated Technology Limited | Wholesale & retail | 1989 |
| Consolv Limited | Professional & scientific | 2017 |
| Construction Services Plus Ltd | Construction | 2015 |
| Consult Legal Advisors Limited | Professional & scientific | 2023 |
| Consult Physio Limited | Health & social care | 2013 |
| Consultancy, Project and Interim Management Services Ltd | Professional & scientific | 2021 |
| Consulting 101 Ltd | Information & communication | 2012 |
| Consulting Networks Ltd | Information & communication | 2003 |
| Consulting Things Ltd | Information & communication | 2022 |
| Consultionz Ltd | Information & communication | 2018 |
| Contain the Move Ltd | Transport & logistics | 2026 |
| Content Craze Ltd | Information & communication | 2025 |
| Continental Deli Ltd | Hospitality | 2018 |
| Continuum ARC Ltd | Wholesale & retail | 2025 |
| Continuum Growth Ltd | Hospitality | 2026 |
| Contract Blinds Services Ltd | Manufacturing | 2019 |
| Contract Equipment Ltd. | Real estate | 2003 |
| Contractor Lettings Ltd | Real estate | 2023 |
| Contrafill Limited | Information & communication | 2023 |
| Control Design and Development Limited | Information & communication | 2020 |
| Controls Engineering Solutions Ltd | Professional & scientific | 2019 |
| Convert Media Ltd | Information & communication | 2015 |
| Conveyance Singh Ltd | Professional & scientific | 2019 |
| Conworth Close Management Company Limited | Real estate | 2005 |
| Cook and Mackelvie Limited | Wholesale & retail | 1994 |
| Cookco Catering Equipment Limited | Administrative & support | 2014 |
| Cookes Property Management Limited | Real estate | 2009 |
| Cookhouse Xpress Ltd | Hospitality | 2024 |
| Cool Bar 22 Ltd | Hospitality | 2022 |
| Cool Move AV Ltd | Transport & logistics | 2024 |
| Cool Move Kali Ltd | Transport & logistics | 2019 |
| Coolheatuk Ltd | Construction | 2021 |
| Coolkatzcraft Ltd | Professional & scientific | 2018 |
| Coolmoss (UK) Ltd | Real estate | 2012 |
| Coolsite Ltd | Professional & scientific | 2000 |
| Cooper Energy Engineering Limited | Professional & scientific | 2012 |
| Cooperm Home Improvements Limited | Water & waste | 2020 |
| Coopers Car & Commercial Services Limited | Wholesale & retail | 2022 |
| Copaclue Limited | Wholesale & retail | 2026 |
| Cope Healthcare Ltd | Administrative & support | 2022 |
| Coperion UK Limited | Manufacturing | 2006 |
| Copia Lets Ltd | Real estate | 2013 |
| Copper Sprocket Ltd | Information & communication | 2022 |
| Copsewood Capital Corp Ltd | Real estate | 2024 |
| Copytech (UK) Limited | Manufacturing | 1995 |
| Coraggio & Leslie Associates Ltd | Professional & scientific | 2022 |
| Coral Care Ltd | Health & social care | 2023 |
| Coral Property Management Ltd | Real estate | 2017 |
| Corban Global Limited | Education | 2022 |
| Corbmar Ltd | Construction | 2026 |
| Corby Care Homes Limited | Health & social care | 2020 |
| Cordant Ltd | Wholesale & retail | 2025 |
| Corder Physio Ltd | Health & social care | 2014 |
| Cordoba-Christie Ltd | Health & social care | 2026 |
| Core Bathroom Installations Limited | Construction | 2021 |
| Core Construction & Developments Limited | Construction | 2020 |
| Core Utility Solutions Limited | Information & communication | 2024 |
| Cornel Haulage Ltd | Transport & logistics | 2024 |
| Cornelis Trans Ltd | Transport & logistics | 2014 |
| Corner Express Shop PB Ltd | Wholesale & retail | 2024 |
| Corner Farm Management Company Limited | Households | 2016 |
| Corner Food Ltd | Wholesale & retail | 2013 |
| Cornerstone Lets Ltd | Real estate | 2025 |
| Cornerstone Property Holdings Corp Ltd | Real estate | 2025 |
| Cornerstone Property Partnership Limited | Professional & scientific | 2025 |
| Coromandel Productions Ltd | Arts & recreation | 2008 |
| Corona DI Ricchezza UK Limited | Construction | 2016 |
| Coroni Technology Ltd | Information & communication | 2004 |
| Corporate Control Limited | Professional & scientific | 1997 |
| Corporate Courier Logistics Ltd | Transport & logistics | 2022 |
| Corporate Property Hosts Limited | Real estate | 2021 |
| Corrin Software Products Limited | Information & communication | 1994 |
| Cortland Bidco Limited | Financial services | 2019 |
| Cortland Midco 1 Limited | Financial services | 2019 |
| Cortland Midco 2 Limited | Financial services | 2019 |
| Cortland Topco Limited | Financial services | 2019 |
| Corva Health Consulting Limited | Public administration | 2026 |
| Corvo Consulting Ltd | Construction | 2026 |
| Corvus Financial Limited | Professional & scientific | 2019 |
| Corwin's Idea Ltd | Wholesale & retail | 2022 |
| Coscat Trans Limited | Construction | 2022 |
| Cosdus Ltd | Information & communication | 2024 |
| Cosmicmaker Ltd | Professional & scientific | 2026 |
| Cosmos Property Investments Limited | Real estate | 2017 |
| Costa Removals Ltd | Transport & logistics | 2025 |
| Costin ION Ltd | Transport & logistics | 2016 |