| Colin Parker (Masonry) Limited | Manufacturing | 1975 |
| Collin Russon Builders Limited | Construction | 2010 |
| Combilo UK Ltd | Wholesale & retail | 2024 |
| Commercial Garage Ltd | Wholesale & retail | 2022 |
| Community Rural Environmental Asset Transformation Enterprise Limited | Administrative & support | 2022 |
| Compass Concrete Ltd | Manufacturing | 2026 |
| Complete Construction Services Limited | Construction | 2018 |
| Complete Home Care Services Ltd | Construction | 2025 |
| Complete Home Improvement Ltd | Construction | 2019 |
| Completely Ordinary Limited | Real estate | 2012 |
| Compton Heating Limited | Construction | 2015 |
| Compton Lodge Properties Limited | Hospitality | 2022 |
| Conac Trans Ltd | Transport & logistics | 2024 |
| Concept 2 Solutions Limited | Manufacturing | 2013 |
| Conceptual Exploration Research Ltd | Professional & scientific | 2022 |
| Connect Beds Limited | Wholesale & retail | 2007 |
| Connell Property Limited | Real estate | 2008 |
| Connexus Electrical Ltd | Construction | 2020 |
| Constant Endeavour Limited | Professional & scientific | 2014 |
| Constantin Pascal Transport Ltd | Transport & logistics | 2015 |
| Container JOE Limited | Administrative & support | 2009 |
| Contemporary Angels Limited | Other services | 2017 |
| Contove Ltd | Wholesale & retail | 2026 |
| Contract Rite Limited | Professional & scientific | 2020 |
| Contril Ltd | Professional & scientific | 2025 |
| Controllis Limited | Professional & scientific | 2008 |
| Cooks Driving Success Ltd | Education | 2025 |
| Cooling Solutions Limited | Construction | 2014 |
| Cooperworks Auto Repairs Ltd | Wholesale & retail | 2025 |
| Copelade Services Ltd | Professional & scientific | 2025 |
| Copper Cable Recycling Ltd | Wholesale & retail | 2022 |
| COR DU Marketing Limited | Agriculture & fishing | 1999 |
| Corevolt Limited | Construction | 2023 |
| Corn Exchange Apex Ltd | Hospitality | 2020 |
| Corn Exchange Courtyard Ltd | Hospitality | 2020 |
| Corn Exchange Drinkery Ltd | Hospitality | 2020 |
| Corn Exchange Newark Ltd | Hospitality | 2020 |
| Corn Exchange Spot Ltd | Hospitality | 2020 |
| Cornerstone Construction (Lincs) Ltd | Construction | 2026 |
| Cornfields (Flats) Management Company Limited | Hospitality | 1990 |
| Cornwell & Sons Limited | Transport & logistics | 2009 |
| Corny Trans Ltd | Transport & logistics | 2021 |
| Coronation Bars Limited | Hospitality | 2019 |
| Corr Developments Limited | Construction | 2020 |
| Corvin FOX Holdings Ltd | Financial services | 2022 |
| Corvin FOX Ltd | Professional & scientific | 2008 |
| Cosadtrans Ltd | Transport & logistics | 2023 |
| Costi & Daria Ltd | Administrative & support | 2016 |
| Costyflavor Trans Ltd | Transport & logistics | 2015 |
| Cots World Roofing Ltd | Construction | 2026 |
| Cotton's Properties Limited | Extraterritorial | 2017 |
| Country Court Care Group Contracting Limited | Health & social care | 2021 |
| Country Court Care Group Holdings Limited | Health & social care | 2018 |
| Country Court Care Group Limited | Financial services | 2015 |
| Country Court Care Homes 10 Limited | Health & social care | 2023 |
| Country Court Care Homes 11 Opco Limited | Health & social care | 2024 |
| Country Court Care Homes 12 Opco Limited | Health & social care | 2024 |
| Country Court Care Homes 13 Opco Limited | Health & social care | 2024 |
| Country Court Care Homes 14 Limited | Construction | 2021 |
| Country Court Care Homes 15 Opco Limited | Real estate | 2024 |
| Country Court Care Homes 16 Holdco Limited | Health & social care | 2025 |
| Country Court Care Homes 17 Opco Limited | Health & social care | 2025 |
| Country Court Care Homes 17 Propco Limited | Construction | 2025 |
| Country Court Care Homes 18 Opco Limited | Health & social care | 2025 |
| Country Court Care Homes 18 Propco Limited | Construction | 2025 |
| Country Court Care Homes 19 Opco Limited | Health & social care | 2025 |
| Country Court Care Homes 19 Propco Limited | Construction | 2025 |
| Country Court Care Homes 2 Limited | Health & social care | 2014 |
| Country Court Care Homes 2 Propco Limited | Construction | 2015 |
| Country Court Care Homes 3 Opco Limited | Health & social care | 2015 |
| Country Court Care Homes 3 Propco Limited | Real estate | 2015 |
| Country Court Care Homes 5 Limited | Health & social care | 2016 |
| Country Court Care Homes 6 Limited | Health & social care | 2020 |
| Country Court Care Homes 7 Opco Limited | Health & social care | 2020 |
| Country Court Care Homes 8 Limited | Health & social care | 2021 |
| Country Court Care Homes 9 Limited | Health & social care | 2023 |
| Country Court Care Homes Limited | Health & social care | 1996 |
| Countryside Home Management Limited | Real estate | 2022 |
| County Fire and Security Limited | Construction | 2012 |
| County Kitchens (Pinchbeck) Limited | Wholesale & retail | 1980 |
| County Roofline Ltd | Construction | 2024 |
| Couture Cakes Limited | Manufacturing | 2009 |
| Couvia 1 Limited | Real estate | 2025 |
| Couvia 2 Limited | Real estate | 2025 |
| Couvia 3 Limited | Real estate | 2025 |
| Covaci Transport Ltd | Transport & logistics | 2019 |
| Cover of London Ltd | Wholesale & retail | 2026 |
| Coveris Flexibles (Gainsborough) UK Limited | Manufacturing | 2003 |
| Coveris Flexibles Holdings UK Limited | Financial services | 2012 |
| Coveris Speciality Bags Limited | Manufacturing | 1987 |
| Covers of London Ltd | Wholesale & retail | 2026 |
| Coyne Finance Ltd | Public administration | 2024 |
| CPT Distribution Limited | Transport & logistics | 1995 |
| CR Removals Ltd | Transport & logistics | 2025 |
| Craftex Carpentry Ltd | Manufacturing | 2025 |
| Crafty Monkies Ltd | Arts & recreation | 2019 |
| Craig Youngs Transport Limited | Transport & logistics | 2022 |
| Crawling Panther Tattoo Parlour Ltd | Other services | 2020 |
| CRD Contractors Ltd | Construction | 2016 |
| Creasey Electrical Ltd | Construction | 2023 |