| Conducive Housing Ltd | Real estate | 2016 |
| Confero Partners Limited | Professional & scientific | 2025 |
| Confidentia UK Limited | Administrative & support | 2019 |
| Confluence Media Limited | Information & communication | 2018 |
| Confluence Productions Limited | Information & communication | 2026 |
| Conisbee Limited | Real estate | 1956 |
| Conmoy Construction Co. Limited | Wholesale & retail | 1969 |
| Connect Claims Group Ltd | Professional & scientific | 2025 |
| Connections at Home Limited | Wholesale & retail | 2008 |
| Connell Air Conditioning Limited | Construction | 2010 |
| Connemara Ltd | Real estate | 2018 |
| Conplan Ltd | Administrative & support | 2015 |
| Consilium Legal Limited | Professional & scientific | 2005 |
| Consterdine Ltd | Construction | 2023 |
| Construction Communication Limited | Professional & scientific | 2026 |
| Construction Finishing Solutions Limited | Construction | 2015 |
| Construction Health and Safety Services Ltd | Other services | 2017 |
| Construction Health and Safety Solutions Ltd | Other services | 2011 |
| Construction Management DF Limited | Administrative & support | 2017 |
| Constructiononsitemanagement Ltd | Construction | 2019 |
| Constructive Moves (Residential) Limited | Administrative & support | 2017 |
| Constructive Moves Limited | Administrative & support | 2021 |
| Consult Procure Manage Limited | Professional & scientific | 2023 |
| Contafinvest Enterprises Limited | Mining & quarrying | 2005 |
| Container Applications International (U.K.) Limited | Administrative & support | 1994 |
| Contempo Designs Limited | Construction | 2003 |
| Contemporary Concrete Flooring Ltd | Other services | 2014 |
| Content Creation Shop London Ltd | Professional & scientific | 2025 |
| Continuing Care Support Ltd | Health & social care | 2021 |
| Contour Media Ltd | Information & communication | 2016 |
| CONV3RT Marketing Limited | Information & communication | 2023 |
| Convi Group Ltd | Administrative & support | 2024 |
| Cook Homes Limited | Real estate | 2025 |
| Cool Breeze Air Conditioning Solutions Limited | Energy | 2025 |
| Cool Installs Ltd | Construction | 2011 |
| Coolbergen Management Limited | Households | 2021 |
| Coolbergen Properties Limited | Real estate | 2008 |
| Coop Capital Ltd | Real estate | 2026 |
| Cooper Family Estates Limited | Construction | 2025 |
| Cooper Homes Limited | Construction | 2003 |
| Cooper-Gibson Limited | Professional & scientific | 2009 |
| Coops Solutions Ltd | Information & communication | 2016 |
| Coote Advisory Ltd | Professional & scientific | 2025 |
| Copland Consultancy Ltd | Professional & scientific | 2017 |
| Copperfield Electrical Limited | Construction | 2024 |
| Coptfold Dental Ltd | Health & social care | 2017 |
| Coradale Limited | Information & communication | 2000 |
| Coral Voyages Ltd | Wholesale & retail | 2019 |
| Corbets Place Developments Limited | Construction | 2014 |
| Corbets TEY Developments II Limited | Construction | 2014 |
| Cordell Cars Limited | Wholesale & retail | 2017 |
| Core Club Reformer Pilates Ltd | Arts & recreation | 2024 |
| Core Education UK Limited | Education | 2007 |
| Core Housing Solutions Ltd | Real estate | 2026 |
| Core Refurbishments Limited | Construction | 2020 |
| Corefit Hub Limited | Wholesale & retail | 2025 |
| Corkr Fine Wines Limited | Wholesale & retail | 2009 |
| Cornerstone Digital Group Ltd | Professional & scientific | 2026 |
| Cornerstone Investment Management Limited | Financial services | 2021 |
| Cornish Holiday Lets Limited | Hospitality | 2021 |
| Coro Spezzato Limited | Administrative & support | 2021 |
| Coromel Limited | Agriculture & fishing | 2019 |
| Corporate Commercial Collections Limited | Financial services | 2011 |
| Corrigan Specialist Services Ltd | Other services | 2014 |
| Cosecpro Ltd | Professional & scientific | 2021 |
| Cosmic Electronics Ltd | Professional & scientific | 2003 |
| Coss Printing Services Ltd | Professional & scientific | 2005 |
| Costello Music School Ltd | Education | 2025 |
| Cotham Limited | Administrative & support | 2017 |
| Cotton Nest Ltd | Wholesale & retail | 2026 |
| Counselling Mentoring and Mindfulness Ltd. | Health & social care | 2017 |
| Country Places Residential Lettings Limited | Real estate | 2008 |
| Countryside (UK) Limited | Extraterritorial | 2002 |
| Countryside 27 Limited | Real estate | 2007 |
| Countryside Abri Ford North LLP | | 2024 |
| Countryside Clarion (Eastern Quarry) LLP | | 2018 |
| Countryside L&Q (Beaulieu) LLP | | 2008 |
| Countryside L&Q (North East Chelmsford) LLP | | 2021 |
| Countryside L&Q (Oaks Village) LLP | | 2015 |
| Countryside Maritime Limited | Construction | 1990 |
| Countryside Neptune LLP | | 2007 |
| Countryside Places for People (Cowley Hill) LLP | | 2022 |
| Countryside Places for People (Lower Herne) LLP | | 2021 |
| Countryside Places for People Lower Herne Management Company Limited | Households | 2023 |
| Countryside Properties (Bicester) Limited | Real estate | 2001 |
| Countryside Properties (Booth Street 2) Limited | Professional & scientific | 2001 |
| Countryside Properties (Merton Abbey Mills) Limited | Professional & scientific | 2002 |
| Countryside Properties (Salford Quays) Limited | Extraterritorial | 2002 |
| Countryside Properties Residential (ABC) Limited | Households | 2021 |
| Countryside Properties Residential (Chelmsford) Limited | Households | 2021 |
| Countryside Properties Residential (Dartford) Limited | Households | 2021 |
| Countryside Residential (South Thames) Limited | Extraterritorial | 1992 |
| Countryside Residential (South West) Limited | Extraterritorial | 1992 |
| Countryside Seven Limited | Extraterritorial | 2002 |
| Countryside Sigma Limited | Construction | 2006 |
| Countryside Sovereign Swindon LLP | | 2021 |
| Countryside Spaces Ltd | Construction | 2023 |
| Countrywide Civils Ltd | Construction | 2021 |
| County Coaches(Brentwood)Limited | Transport & logistics | 1962 |
| County Hearing Care Ltd | Wholesale & retail | 2018 |