| Construction Entity Corporation Limited | Construction | 2023 |
| Construction Investigation Group Services Limited | Professional & scientific | 2020 |
| Construction Plant Ltd | Construction | 2019 |
| Construction Recruitment Solutions Ltd. | Administrative & support | 2014 |
| Construction Specialist Group Limited | Construction | 2019 |
| Constructions and Buildings UK Limited | Construction | 2019 |
| Constructo Ltd | Construction | 2025 |
| Consult GT Limited | Professional & scientific | 2022 |
| Consultalogix LLP | | 2025 |
| Consultancy 22 Ltd | Professional & scientific | 2022 |
| Consultant SG Group Limited | Administrative & support | 2019 |
| Consultants in Care Limited | Real estate | 2000 |
| Consulting Ventures Limited | Information & communication | 2012 |
| Consummate Building Consultancy Ltd | Construction | 2020 |
| Consummate Property Management Ltd | Real estate | 2022 |
| Consurgoservices Limited | Administrative & support | 2013 |
| Contact 4 Support Services Limited | Administrative & support | 2006 |
| Contact Commercial Limited | Hospitality | 2005 |
| Container Projects LLP | | 2012 |
| Contemporary Tech Solutions Ltd | Water & waste | 2026 |
| Contentall Limited | Professional & scientific | 2018 |
| Contexa Digital Ltd | Information & communication | 2023 |
| Context Checks Ltd | Administrative & support | 2018 |
| Continental Cash & Carry Limited | Wholesale & retail | 2014 |
| Continental Commerce Consultancy Ltd | Professional & scientific | 2020 |
| Contingency Recruitment Limited | Information & communication | 2019 |
| Continuum AI Ltd | Professional & scientific | 2025 |
| Contract Cleaning & Facilities Ltd | Administrative & support | 2011 |
| Contractors APS Ltd | Professional & scientific | 2017 |
| Contractors Team Ltd | Construction | 2018 |
| Contras International Innovations Limited | Manufacturing | 2010 |
| Controls Alliance Ltd | Professional & scientific | 2014 |
| Convedior Limited | Professional & scientific | 2008 |
| Conveno Limited | Professional & scientific | 2020 |
| Convergence Business Solutions Ltd | Information & communication | 2021 |
| Converse Interpreting Ltd | Professional & scientific | 2026 |
| Conversion Grid Ltd | Information & communication | 2026 |
| Conversion-Uk Ltd | Administrative & support | 2012 |
| Convertibles Only Ltd | Wholesale & retail | 2017 |
| Convo & Co UK Limited | Professional & scientific | 2024 |
| Cooden Consulting Limited | Professional & scientific | 2013 |
| Cookies Media Ltd | Professional & scientific | 2017 |
| Cookin LAB Limited | Hospitality | 2019 |
| Cookin LAB Services Limited | Hospitality | 2025 |
| Cool Accountancy Solutions Ltd | Professional & scientific | 1998 |
| Cool Breeze Contracting Ltd | Energy | 2025 |
| Cool I.T. Solutions Limited | Information & communication | 1997 |
| Cool Leaf Limited | Wholesale & retail | 2020 |
| Cool Music Empire Limited | Information & communication | 2024 |
| Coolered Films Ltd | Professional & scientific | 2023 |
| Coolheads Consultancy Ltd | Professional & scientific | 2015 |
| Coolheat Solutions Service Ltd | Other services | 2022 |
| Cooling Services Ltd | Professional & scientific | 2019 |
| Coombe Lane (Property) Ltd | Real estate | 2021 |
| Coombe Road (6-8) LLP | | 2018 |
| Coombe Trading & Marketing - Two Limited | Construction | 2021 |
| Coombe Trading and Marketing - One Limited | Construction | 2021 |
| Coombe Valley Road Management Company Limited | Real estate | 2019 |
| Cooperace Ltd | Information & communication | 2024 |
| Coopers 2 U Limited | Construction | 2018 |
| Cooperscroft Care Home Limited | Health & social care | 2012 |
| Coorg Kaapi (UK ) Limited | Hospitality | 2019 |
| Coorg Kaapi Ltd | Hospitality | 2019 |
| Coorvai Ltd | Construction | 2013 |
| Cootes Holdings Limited | Financial services | 2018 |
| Cootes Properties Limited | Real estate | 2017 |
| Copbay Limited | Real estate | 2017 |
| Copeland Services Ltd | Administrative & support | 2005 |
| Coperl Limited | Real estate | 2026 |
| Copetown Limited | Real estate | 1979 |
| Coplan Associates UK Limited | Other services | 2018 |
| Cople Car Sales Ltd | Wholesale & retail | 2024 |
| Copper London Limited | Administrative & support | 2006 |
| Coppermill Care Limited | Health & social care | 2002 |
| Coppermill Estates Ltd | Real estate | 2022 |
| Copsham House (Chesham) Management Company Limited | Households | 2014 |
| COPTHORNE71 Limited | Real estate | 2019 |
| Copy and Space Ltd | Professional & scientific | 2021 |
| Coral Labs Holding Ltd | Financial services | 2026 |
| Corderoy International Limited | Professional & scientific | 1981 |
| Core Electrical Solutions Ltd | Construction | 2007 |
| Core Fleet Innovations Limited | Information & communication | 2022 |
| Core Harmony Ltd | Arts & recreation | 2026 |
| Core Microsystems Ltd | Information & communication | 2007 |
| Core Property Partners Ltd | Real estate | 2025 |
| Coreceleste Limited | Manufacturing | 2025 |
| Coredata Cabling Ltd | Information & communication | 2026 |
| Corefront Security Group Ltd | Administrative & support | 2025 |
| Coregrowth Capital Limited | Financial services | 2026 |
| Corella Consulting Limited | Information & communication | 2016 |
| Corelli (Shooters Hill) LLP | | 2022 |
| Corelli Amenities Ltd | Households | 2025 |
| Corelli Homes Limited | Real estate | 2021 |
| Corepeople Consulting Ltd | Professional & scientific | 2025 |
| Coretonomy Limited | Information & communication | 2019 |
| Corfu Gyros Ltd | Hospitality | 2025 |
| Coriander House Limited | Hospitality | 2002 |
| Corib Trading Limited | Professional & scientific | 1996 |
| Cork Oak Cars Ltd | Wholesale & retail | 2013 |
| Corlona Ltd | Construction | 2019 |