| Construction Leaders' Club Limited | Professional & scientific | 2013 |
| Construction Services MF Limited | Construction | 2021 |
| Construction Skills Training Solutions Ltd | Public administration | 2014 |
| Construction Training Hub Ltd | Professional & scientific | 2025 |
| Construction Trustee Limited | Other services | 2025 |
| Construction Waste Portal Limited | Information & communication | 2021 |
| Construction-Wise Limited | Construction | 2018 |
| Constructive Choice Ltd | Manufacturing | 2016 |
| Consult AH Ltd | Professional & scientific | 2018 |
| Consult Healthcare Limited | Health & social care | 2005 |
| Consult Holt Limited | Professional & scientific | 2024 |
| Consult Leaders Limited | Professional & scientific | 2024 |
| Consult RK Limited | Professional & scientific | 2019 |
| Consult Ukgp Limited | Health & social care | 2025 |
| Consultancy 4 YOU Ltd | Hospitality | 2016 |
| Consultapharm Ltd | Health & social care | 2023 |
| Consulting by Taiken Ltd | Real estate | 2024 |
| Consulto Ltd | Information & communication | 2016 |
| Consultus Group Limited | Administrative & support | 2023 |
| Consume the Make Ltd | Wholesale & retail | 2025 |
| Consumer Insights Limited | Professional & scientific | 2026 |
| Consumer Marketing Systems and Services Limited | Professional & scientific | 2004 |
| Contact Voice & Data Ltd | Information & communication | 2003 |
| Container Global Ltd | Transport & logistics | 2016 |
| Contemporary Developments Midlands Ltd | Construction | 2015 |
| Content King Marketing Limited | Professional & scientific | 2022 |
| Content Networks Limited | Information & communication | 2009 |
| Content Over Common Sense Marketing Ltd | Information & communication | 2019 |
| Content Proficiency Ltd | Information & communication | 2022 |
| Continental Auto Parts Limited | Wholesale & retail | 2011 |
| Continental Business and Services Ltd | Administrative & support | 2019 |
| Continental Direct UK Limited | Wholesale & retail | 2000 |
| Continental Stores (UK) Limited | Wholesale & retail | 2006 |
| Continuous Fashion Ltd | Professional & scientific | 2018 |
| Continuum Business Services Limited | Professional & scientific | 2015 |
| Contour Surveying and Engineering Ltd | Construction | 2014 |
| Contoure Ltd | Administrative & support | 2014 |
| Contract Floor Installations Limited | Professional & scientific | 2008 |
| Contract Flooring Association Limited | Administrative & support | 1974 |
| Contract Furniture Group Limited | Wholesale & retail | 2009 |
| Contract Packaging Services Limited | Manufacturing | 2002 |
| Contracts Eco Limited | Other services | 2017 |
| Contrech Limited | Construction | 2025 |
| Control and Safety ENG Ltd | Professional & scientific | 2006 |
| Control Stream Ltd | Manufacturing | 2009 |
| Control Tower Newton Limited | Hospitality | 2019 |
| Controliss Limited | Wholesale & retail | 2009 |
| Controlled Car Parks Ltd | Administrative & support | 2025 |
| Convenient and Reliable Ltd | Wholesale & retail | 2023 |
| Converged Technology Services Ltd | Information & communication | 2012 |
| Conveyancing Connoisseurs Limited | Information & communication | 2024 |
| Conveyancing Excellence Training Hub Ltd | Education | 2024 |
| Convista Consulting Limited | Information & communication | 2001 |
| Cook Cool Catering Supplies Ltd | Wholesale & retail | 2020 |
| Cook Hook Ltd | Hospitality | 2019 |
| Cook Production Limited | Professional & scientific | 2025 |
| Cooke Digital Ltd | Manufacturing | 2021 |
| Cookie Club 23 UK Ltd | Education | 2021 |
| Cookieshake UK Limited | Hospitality | 2006 |
| Cookson & SON Limited | Construction | 2005 |
| Cooksons Accountants Limited | Extraterritorial | 2002 |
| Cook’S Tidy Limited | Hospitality | 2019 |
| Cool 4 U Ltd | Financial services | 2024 |
| Cool and Cozy Properties Ltd | Real estate | 2025 |
| Cool Code Company Ltd | Information & communication | 2008 |
| Cool Drink and Food Ltd | Wholesale & retail | 2024 |
| Cool Genes Community Interest Company | Health & social care | 2024 |
| Cool Packaging Holdings Ltd | Financial services | 2022 |
| Cool Skin Studio Ltd | Other services | 2026 |
| Cool-Pin Limited | Information & communication | 2022 |
| Cooled Motors Ltd | Manufacturing | 2025 |
| Coolingconditioning Ltd | Manufacturing | 2024 |
| Coolstream Ventilation Ltd | Manufacturing | 2009 |
| Coolways-Uk Ltd | Manufacturing | 2022 |
| Cooner Investments Limited | Financial services | 2022 |
| Cooney's Engineering Limited | Construction | 2015 |
| Cooper & Berry,Limited | Wholesale & retail | 1938 |
| Cooper & Jones Ltd. | Professional & scientific | 1993 |
| Cooper and Cooper Holdings Ltd | Real estate | 2025 |
| Cooper Family Holdings Limited | Financial services | 2023 |
| Cooper Fire and Security Ltd | Other services | 2019 |
| Cooper Research Technology Limited | Manufacturing | 1989 |
| Cooper Richardson Ltd | Real estate | 2023 |
| Cooper Social Finance Limited | Information & communication | 2024 |
| Cooperate Home Healthcare- Ltd | Health & social care | 2022 |
| Coosh Bakery Limited | Manufacturing | 2022 |
| Copa Consultancy Limited | Professional & scientific | 2025 |
| Copavida Properties Ltd | Real estate | 2021 |
| Copaz Limited | Construction | 2022 |
| Cope Occupational Health Services Limited | Health & social care | 1997 |
| Copford Dwellings Limited(The) | Real estate | 1946 |
| Copley & Daughter Electrical Ltd | Construction | 2020 |
| Copley Holdings Limited | Financial services | 2020 |
| Copley Property Limited | Construction | 2021 |
| Copley Scientific Limited | Manufacturing | 1978 |
| Copley,Marshall & Co.,Limited | Extraterritorial | 1899 |
| Copper & Bailey Limited | Other services | 2025 |
| Copper EYE Photography Limited | Professional & scientific | 2008 |
| Copper Music Ltd | Information & communication | 2026 |
| Copper Plumbing Solutions Ltd | Construction | 2021 |