| Clayton & Co. Property Ltd | Real estate | 2026 |
| Clayton Drylining Limited | Construction | 2025 |
| CLEAN24 Ltd | Information & communication | 2021 |
| Cleanaway Property Services Limited | Other services | 2012 |
| Cleaning Expert 24-7 Ltd | Administrative & support | 2014 |
| Clear BID Solutions Limited | Professional & scientific | 2014 |
| Clear Brew Northants Limited | Administrative & support | 2019 |
| Clear One Accounting Limited | Professional & scientific | 2026 |
| Clearsands Ltd | Real estate | 2018 |
| Clearwater Softeners Limited | Administrative & support | 2003 |
| Clearword Limited | Professional & scientific | 2008 |
| Clement Services Ltd | Professional & scientific | 2022 |
| Clementine and Rafe Ltd | Wholesale & retail | 2026 |
| Cleomack (One) Limited | Extraterritorial | 1988 |
| Cleomack (Three) Limited | Extraterritorial | 1962 |
| Cleomack Limited | Extraterritorial | 1959 |
| Cleveland & Co UK Ltd | Real estate | 2016 |
| Cleveland Properties Private Ltd | Real estate | 2020 |
| Cleveland Square Properties (London) Limited | Professional & scientific | 1951 |
| Cleverclip Ltd | Manufacturing | 2024 |
| Cleverhall Ltd | Professional & scientific | 2002 |
| CLF Construction Ltd | Construction | 2022 |
| CLG Air Conditioning Services Limited | Energy | 2002 |
| CLG Kettering Limited | Other services | 2013 |
| Click & Cook Limited | Manufacturing | 2025 |
| Click Conscious Ltd | Professional & scientific | 2020 |
| Click HR Limited | Professional & scientific | 2008 |
| CLICK4PCS Ltd | Wholesale & retail | 2004 |
| Clickcare Limited | Health & social care | 2022 |
| Clickconvert Ltd | Professional & scientific | 2026 |
| Clifford White Medicolegal Limited | Professional & scientific | 2014 |
| Clifton House (Kettering) Management Limited | Extraterritorial | 2001 |
| Clifton Roofing Group Ltd | Construction | 2025 |
| Clifton Works Ltd | Extraterritorial | 2020 |
| Climb Property Development Limited | Real estate | 2023 |
| Climb Property Management Limited | Real estate | 2023 |
| Climb Property Services Limited | Construction | 2023 |
| Clip Accounting Solutions Ltd | Professional & scientific | 2026 |
| Clipstone Masonry Ltd | Manufacturing | 2025 |
| Clive Hodges Consulting Limited | Professional & scientific | 2024 |
| CLM Landscapes Ltd | Administrative & support | 2018 |
| Cloud Fourteen Properties Ltd | Households | 2019 |
| Cloudy 2 Clear Northampton Limited | Construction | 2009 |
| Clover Coffee Events Limited | Hospitality | 2025 |
| Clss Brunswick Place Limited | Construction | 2015 |
| Club 99 Barbering Ltd | Other services | 2025 |
| Club 99 Limited | Other services | 2020 |
| CM & Constructions Ltd | Construction | 2024 |
| CM Roofing Installations Limited | Construction | 2023 |
| CMB Drivers Ltd | Transport & logistics | 2010 |
| CMD Careers Ltd | Professional & scientific | 2025 |
| CMD Property Services Ltd. | Construction | 2014 |
| CMJ IT Limited | Information & communication | 2023 |
| Cmjtransports Ltd | Transport & logistics | 2024 |
| Cmmth Medical Ltd | Health & social care | 2014 |
| CMS Kettering Ltd | Real estate | 2019 |
| CMS Networx Ltd | Financial services | 2019 |
| CNL Commercial Ltd | Wholesale & retail | 2025 |
| Co Creative Studio Ltd | Professional & scientific | 2026 |
| Co-Living Abodes Ltd | Real estate | 2022 |
| Coach Consulting Ltd | Professional & scientific | 2023 |
| Coastbond Holdings Limited | Financial services | 2016 |
| Coastbond Limited | Wholesale & retail | 1990 |
| Cobbold Associates Ltd | Financial services | 2012 |
| Coco's Kettering Ltd | Other services | 2018 |
| Code Property Developments Limited | Real estate | 2005 |
| Cofee House Amore Ltd | Hospitality | 2018 |
| Cold Mirror Ltd | Manufacturing | 2025 |
| Coles Commercial Services Ltd | Professional & scientific | 2023 |
| Coles for Fires Limited | Construction | 2013 |
| Colewick Limited | Wholesale & retail | 2015 |
| Colindale Rabbit Limited | Wholesale & retail | 2014 |
| Colinz Ltd | Health & social care | 2022 |
| Collyweston Stone Slating Trust Limited | Education | 1982 |
| Coloured Cotton Limited | Wholesale & retail | 2017 |
| Colson Holdings Limited | Financial services | 2009 |
| Columbus Fifty Nine Ltd | Financial services | 2021 |
| Combined Motors Limited | Wholesale & retail | 2003 |
| Command UK Limited | Professional & scientific | 2004 |
| Commspower (UK) Services Ltd | Construction | 2010 |
| Communication South West Ltd | Administrative & support | 2023 |
| Communicore Limited | Administrative & support | 2025 |
| Community Coworking Ltd | Real estate | 2021 |
| Company 99 Limited | Administrative & support | 2008 |
| Compass Children's Charity | Education | 1998 |
| Complete Computer Services Ltd | Information & communication | 2019 |
| Complexus Care Limited | Health & social care | 2021 |
| Complexus Holdings Limited | Financial services | 2021 |
| Compliance Accounting Limited | Professional & scientific | 2023 |
| Compton & Clarke Limited | Administrative & support | 2014 |
| Concave Services Limited | Mining & quarrying | 2018 |
| Concept 2 Reality Events Limited | Professional & scientific | 2016 |
| Concept Domestic Floors Ltd | Wholesale & retail | 2013 |
| Concept Flooring (Kettering) Ltd. | Construction | 1999 |
| Concept Launch Holdings Limited | Financial services | 2023 |
| Concept Launch Partners Ltd | Professional & scientific | 1998 |
| Concept Lets Ltd | Real estate | 2022 |
| Concrete Models Limited | Professional & scientific | 2013 |
| Condor Cold Star Construction Ltd | Construction | 2020 |
| Coney Bakery Limited | Manufacturing | 2018 |