| Christ-In-You Glory Church | Other services | 2011 |
| Cindersmith Limited | Hospitality | 2009 |
| Civillita Ltd | Wholesale & retail | 2024 |
| CL Holiday Homes Limited | Real estate | 2024 |
| Clarity Pathway Limited | Health & social care | 2023 |
| Clarkhill Grooming Services Limited | Other services | 2008 |
| Cleanflow Services Limited | Administrative & support | 2025 |
| Cleaning 2 Shine Ltd | Administrative & support | 2020 |
| Clearpath Land and Civils Limited | Construction | 2026 |
| Clearpilot Ltd | Construction | 2021 |
| Clearways Southern Ltd | Administrative & support | 2017 |
| Clemig Hall Ltd | Professional & scientific | 2021 |
| Cleveria School of Business and Technology (Csbt) Ltd. | Education | 2024 |
| Climax Hvac Ltd | Construction | 2020 |
| Climbing Matrix Ltd | Arts & recreation | 2025 |
| Clive House Management Company Ltd | Real estate | 2022 |
| Cloud INK Limited | Professional & scientific | 2026 |
| Cloud OS Services Limited | Information & communication | 2020 |
| Clouds of London Ltd | Real estate | 2023 |
| Clyde SPV Limited | Financial services | 2017 |
| Co Connect Consulting Ltd | Professional & scientific | 2010 |
| Cobalt Plant Hire Limited | Administrative & support | 2022 |
| Coban & James Limited | Other services | 2021 |
| Cobnuts Construction Ltd | Construction | 2025 |
| Codora Technologies Limited | Information & communication | 2022 |
| Cognian Limited | Information & communication | 2018 |
| Coker Bros. Limited | Professional & scientific | 1981 |
| Coker Couriers Limited | Transport & logistics | 2007 |
| Cole Anaesthetics Services Limited | Health & social care | 2020 |
| Coleshill Parkway Limited | Construction | 2005 |
| Colosseum Contractors Ltd | Construction | 2015 |
| Comforter of the Afflicted Care Limited | Health & social care | 2026 |
| Community Focus & Wellbeing Project CIC | Real estate | 2023 |
| Compass Bridge Limited | Professional & scientific | 2022 |
| Compass Construction & Building Limited | Construction | 2019 |
| Compcare UK Ltd | Administrative & support | 2022 |
| Complete Interior Fit OUT Solution’S Ltd | Construction | 2022 |
| Computercourses Limited | Information & communication | 2009 |
| Comwire Limited | Information & communication | 1975 |
| Conditor Group Limited | Financial services | 2023 |
| Conditor Properties Limited | Construction | 2023 |
| Connectbike UK Limited | Wholesale & retail | 2021 |
| Conpi Contractors Ltd | Construction | 2023 |
| Conrise Limited | Construction | 2017 |
| Consort Healthcare (Blackburn) Funding PLC | Administrative & support | 2002 |
| Consort Healthcare (Blackburn) Holdings Limited | Professional & scientific | 2002 |
| Consort Healthcare (Blackburn) Intermediate Limited | Financial services | 2003 |
| Consort Healthcare (Blackburn) Limited | Administrative & support | 2002 |
| Consort Healthcare (MID Yorkshire) Funding PLC | Health & social care | 2006 |
| Consort Healthcare (MID Yorkshire) Holdings Limited | Health & social care | 2006 |
| Consort Healthcare (MID Yorkshire) Intermediate Limited | Health & social care | 2006 |
| Consort Healthcare (MID Yorkshire) Limited | Health & social care | 2006 |
| Consort Healthcare (Salford) Holdings Limited | Professional & scientific | 2007 |
| Consort Healthcare (Salford) Intermediate Limited | Professional & scientific | 2007 |
| Consort Healthcare (Salford) PLC | Professional & scientific | 2007 |
| Consort Healthcare (Tameside) Holdings Limited | Professional & scientific | 2007 |
| Consort Healthcare (Tameside) Intermediate Limited | Professional & scientific | 2007 |
| Consort Healthcare (Tameside) PLC | Professional & scientific | 2007 |
| Constans Holdings Ltd | Financial services | 2026 |
| Contilearn Limited | Professional & scientific | 2024 |
| Contract Services Next Doors.Com Limited | Manufacturing | 2013 |
| Convert K9 Ltd | Administrative & support | 2026 |
| Cooling Services A1 Ltd | Energy | 2024 |
| Cooperage Content Limited | Manufacturing | 2023 |
| Copeland Yussuf (Properties) Ltd | Real estate | 2014 |
| Copeland Yussuf LLP | | 2012 |
| Copley Properties LLP | | 2020 |
| Cornwall Lounge Limited | Hospitality | 2025 |
| Corporate Hygienics Limited | Administrative & support | 2004 |
| Country Tree Care Ltd | Agriculture & fishing | 2022 |
| Countryside Lettings & Events Limited | Hospitality | 2025 |
| Countyroute (A130) PLC. | Construction | 1999 |
| Countyroute 2 Limited | Professional & scientific | 1997 |
| Countyroute Limited | Construction | 1998 |
| Couperjones Ltd | Professional & scientific | 2020 |
| Cove Creative Ltd | Information & communication | 2011 |
| Cp.Data Ltd | Construction | 2021 |
| Cr-Omni Ltd | Professional & scientific | 2009 |
| Cramer Construction Limited | Construction | 2022 |
| Cramlington Renewable Energy Developments Limited | Energy | 2015 |
| Cratus Building Services Limited | Construction | 2003 |
| Crescent & Coffee Ltd | Hospitality | 2026 |
| Crescent Windows (UK) Limited | Construction | 2004 |
| Cresta Associates Limited | Professional & scientific | 1996 |
| Cross London Trains Finance Company Limited | Financial services | 2012 |
| Cross London Trains Holdco 2 Limited | Financial services | 2011 |
| Cross London Trains Holdco Limited | Financial services | 2012 |
| Cross London Trains Limited | Financial services | 2011 |
| CRS Construction Ltd | Construction | 2023 |
| Crystal Display Systems Limited | Wholesale & retail | 2009 |
| CSB Partnership Limited | Real estate | 2016 |
| CT Roofing and Property Solutions Ltd | Construction | 2025 |
| Cuddles and Glow Wholesale Ltd | Manufacturing | 2026 |
| Curry House Swanley Ltd | Hospitality | 2023 |
| Cusselle Plastering Limited | Construction | 2006 |
| CYB Environmental Limited | Water & waste | 2016 |
| Cyberfend Ltd | Administrative & support | 2019 |
| CZC PAY Limited | Administrative & support | 2021 |
| D & D Technical Construction Ltd | Construction | 2022 |
| D & S Rumble Electrical Services Limited | Construction | 2009 |