| Comparia Ltd | Wholesale & retail | 2025 |
| Compass Accountants Limited | Professional & scientific | 1999 |
| Compass Facilities Ltd | Administrative & support | 2022 |
| Compass Projects Ltd | Construction | 2022 |
| Compass South Limited | Real estate | 2020 |
| Compass Supply Solutions Limited | Wholesale & retail | 1996 |
| Compass Yacht Tenders Limited | Manufacturing | 2013 |
| Compleat Secretariat Services Limited | Administrative & support | 2014 |
| Complete Bathroom Service Limited | Construction | 2016 |
| Complete Contract Furniture Installations Limited | Wholesale & retail | 2016 |
| Complete Engineering Ltd | Professional & scientific | 2025 |
| Complete Leisure Events Limited | Other services | 2008 |
| Compton Venues Limited | Hospitality | 2025 |
| Compustyle Limited | Other services | 2008 |
| Computer Network Installations Limited | Information & communication | 1995 |
| Computethis Ltd | Administrative & support | 2015 |
| Computing in the Cloud Ltd | Information & communication | 2016 |
| Conb Solutions Limited | Professional & scientific | 2014 |
| Concentech Ltd | Information & communication | 2021 |
| Concept Fire & Security Ltd | Administrative & support | 2020 |
| Concept Heating & Property Maintenance Limited | Construction | 2022 |
| Conde Group Limited | Professional & scientific | 2007 |
| Condell Properties Limited | Real estate | 2002 |
| Conekt Consulting Ltd | Professional & scientific | 2022 |
| Config Computer Services Limited | Information & communication | 1994 |
| Congleton Specsavers Hearcare Limited | Wholesale & retail | 2013 |
| Congleton Specsavers Limited | Wholesale & retail | 1989 |
| Congleton Visionplus Limited | Wholesale & retail | 2000 |
| Connect Comply Limited | Professional & scientific | 2026 |
| Connect DSX Ltd | Administrative & support | 2004 |
| Connective Communications Limited | Professional & scientific | 2013 |
| Connex Bidco Limited | Financial services | 2023 |
| Connex Holdco Limited | Financial services | 2023 |
| Connor Farrell Rail Services Limited | Construction | 2023 |
| Conrad Belfort Limited | Arts & recreation | 2016 |
| Conrad Manning Racing Ltd | Administrative & support | 2017 |
| Conradie Associates Limited | Manufacturing | 2025 |
| Consett Specsavers Limited | Wholesale & retail | 2003 |
| Conson Projects Ltd | Construction | 2021 |
| Construct a Stencil Ltd | Construction | 2025 |
| Constructex Group Ltd | Financial services | 2025 |
| Constructex Limited | Construction | 2015 |
| Constructing Culture Ltd | Professional & scientific | 2025 |
| Construction & Landscape Limited | Construction | 2002 |
| Construction and Building Ltd | Construction | 2015 |
| Construction Capital Limited | Real estate | 2010 |
| Construction Management & Consultancy Ltd | Construction | 2025 |
| Consultanci Limited | Professional & scientific | 2014 |
| Consultician Limited | Information & communication | 2018 |
| Contour Access Limited | Construction | 2026 |
| Control Consultancy Limited | Administrative & support | 2002 |
| Controlled Interiors Limited | Construction | 1993 |
| Cookworth Limited | Financial services | 2005 |
| Coolers & Condensers Limited | Manufacturing | 1983 |
| Coolgorilla Ltd | Information & communication | 2017 |
| Coolkote Limited | Wholesale & retail | 2011 |
| Cooper Homewood Limited | Professional & scientific | 2011 |
| Cooper Maverick LLP | | 2015 |
| Cooperfieldsales Ltd | Wholesale & retail | 2026 |
| Coopersurgical Holdings Limited | Financial services | 2015 |
| Coopervision (UK) Holdings Limited | Administrative & support | 2014 |
| Coopervision Global Limited | Wholesale & retail | 2021 |
| Coopervision International Holding Company, LP | | 1989 |
| Coopervision International Limited | Wholesale & retail | 2019 |
| Coopervision Lens Care Limited | Wholesale & retail | 1972 |
| Coopervision Limited | Manufacturing | 1998 |
| Coopervision Manufacturing Limited | Manufacturing | 1992 |
| Copannaby Ltd | Real estate | 2021 |
| Cope Consults Limited | Education | 2009 |
| Copello Ltd | Administrative & support | 2023 |
| Coppergate (Thornetts House) LLP | | 2022 |
| Copperwood Management Ltd | Administrative & support | 2008 |
| Copsey Properties Limited | Real estate | 2022 |
| Coralkerry Limited | Information & communication | 2016 |
| Corbiere Investments (Surbiton) Limited | Construction | 2022 |
| Corbiere Properties (Surbiton) Limited | Construction | 2022 |
| Corby Specsavers Limited | Wholesale & retail | 1992 |
| Corby Visionplus Limited | Wholesale & retail | 1992 |
| Corbyz Limited | Administrative & support | 2007 |
| Cordillera Applications Group UK Limited | Administrative & support | 2019 |
| Core Composites Ltd | Manufacturing | 2025 |
| Core Home Energy Ltd | Construction | 2026 |
| Core Medics Ltd | Health & social care | 2025 |
| Corebridge Europe II Holding Limited | Real estate | 2024 |
| Coretek Limited | Information & communication | 1999 |
| Coriolis Therapy Services Ltd | Health & social care | 2024 |
| Cornercrest Brickwork Ltd | Construction | 2025 |
| Cornerstone Building Surveyors Limited | Real estate | 2018 |
| Cornerstone Developments South Limited | Construction | 2023 |
| Corniche Cleaning Services Limited | Administrative & support | 2004 |
| Cornish Keys Ltd | Real estate | 2025 |
| Cornwall Carpenters Ltd | Construction | 2025 |
| Cornwall Hendra Limited | Construction | 2025 |
| Corolla Landscapes Limited | Administrative & support | 2011 |
| Corporate Carbon Ltd | Professional & scientific | 2021 |
| Corporate Strategy Advisors Limited | Financial services | 2018 |
| Corsican Places Limited | Administrative & support | 1986 |
| Corsican Travel Limited | Administrative & support | 1995 |
| Cortec Global Solutions Ltd | Professional & scientific | 2026 |
| Cortex Property Services Limited | Households | 2024 |