| Colossus Construction Ltd | Construction | 2020 |
| Colourworks Coatings (South) Ltd | Construction | 2004 |
| Comarket Fruit (UK) Ltd. | Wholesale & retail | 1990 |
| Comfort Cleaning Private Limited | Administrative & support | 2025 |
| Commerce Collective 2 UK Limited | Wholesale & retail | 2023 |
| Commerce Collective UK Limited | Wholesale & retail | 2020 |
| Community Care 1ST Services Limited | Administrative & support | 2016 |
| Compendium Golf Ltd | Wholesale & retail | 2020 |
| Complete P.E. Limited | Education | 2017 |
| Complete Roofing & Guttering Limited | Construction | 2022 |
| Complex Training London Limited | Other services | 2016 |
| Computec Group Ltd | Administrative & support | 2000 |
| Concept Furniture Design Ltd | Manufacturing | 2021 |
| Concord Developments Limited | Construction | 2020 |
| Coniferous Ltd | Energy | 2024 |
| Coniferous Renewables Limited | Financial services | 2025 |
| Connect Dealers Limited | Wholesale & retail | 2011 |
| Conscious Events Ltd | Information & communication | 2019 |
| Consciousness at Work Limited | Other services | 2019 |
| Constellar Consultancy Limited | Professional & scientific | 2020 |
| CONSTRUCTFUTURE360 Ltd | Professional & scientific | 2026 |
| Construction Project Management (UK) Ltd | Construction | 2011 |
| Consultancy M Ltd | Professional & scientific | 2026 |
| Contact Journalists Ltd | Information & communication | 2026 |
| Contemporary Walkways Ltd | Construction | 2021 |
| Copacetic Aesthetics Ltd | Other services | 2021 |
| Coralglow Limited | Real estate | 2009 |
| Corcom Communications Limited | Professional & scientific | 2008 |
| Core LV Ltd | Manufacturing | 2022 |
| Core Publishing Group Ltd | Information & communication | 2025 |
| Cornerstone Movements Limited | Professional & scientific | 2026 |
| Corporate Tabs & Labels Ltd | Manufacturing | 2019 |
| Cosmyn Security Ltd | Administrative & support | 2020 |
| Cotall and Stainsby Management Limited | Construction | 2013 |
| Countryside Holdings Limited | Real estate | 2018 |
| Countryside Promotions Limited | Real estate | 2006 |
| County & City Developments Limited | Construction | 2006 |
| Countywide Trading Limited | Administrative & support | 2019 |
| Coupling London Ltd | Construction | 2020 |
| Covent Garden BAG Company Ltd | Wholesale & retail | 2015 |
| Cowries Services Ltd | Information & communication | 2017 |
| Coza International Ltd | Wholesale & retail | 2025 |
| CP Bathroom Products Ltd | Wholesale & retail | 2024 |
| CPE Share Holdings Limited | Professional & scientific | 2020 |
| Cpitech Limited | Professional & scientific | 2026 |
| CPM Service Limited | Construction | 2012 |
| CPP Brickwork Contractors Ltd | Construction | 2014 |
| CR Global Limited | Manufacturing | 2023 |
| CR Investigations Ltd | Professional & scientific | 2012 |
| Crarrison Ltd | Wholesale & retail | 2025 |
| Crave IT Limited | Wholesale & retail | 2024 |
| CRC (London) Limited | Manufacturing | 2012 |
| Cream Deluxe Limited | Hospitality | 2025 |
| Create Property Services Ltd | Real estate | 2019 |
| Creative Fencing & Landscapes Ltd | Construction | 2025 |
| Creative Friction Ltd | Professional & scientific | 2017 |
| Creative Media and Arts Ltd | Professional & scientific | 2020 |
| Crediqo Ltd | Financial services | 2025 |
| Cregeen Consulting Limited | Financial services | 2025 |
| Creme Inc Casting Ltd | Administrative & support | 2019 |
| Crescent Trade Finance LLP | | 2014 |
| Crewfield Limited | Professional & scientific | 2006 |
| Crewfinder Solutions Ltd | Professional & scientific | 2024 |
| Cristal Pharmacy Limited | Wholesale & retail | 2013 |
| Critical Area Cleaning Limited | Administrative & support | 2020 |
| Critical Area Maintenance Ltd | Administrative & support | 2018 |
| CRJ Construction (UK) Limited | Construction | 2014 |
| Croft Projects Limited | Real estate | 2019 |
| Cross 27 Ltd | Wholesale & retail | 2025 |
| Cross Coffee Ltd | Hospitality | 2024 |
| Cross Country Installations Ltd | Construction | 2024 |
| Cross Family Butchers Limited | Wholesale & retail | 2026 |
| Cross Grill & Meat Ltd | Wholesale & retail | 2025 |
| Cross Lane Redcliffe Ltd | Real estate | 2022 |
| Cross Local Ltd | Wholesale & retail | 2025 |
| Cross Mission Church | Other services | 2016 |
| Cross Pizza Ltd | Hospitality | 2024 |
| Cross Tech Online Ltd | Wholesale & retail | 2024 |
| Crowland Cafe Ltd | Hospitality | 2016 |
| Crown Social Care Limited | Health & social care | 2015 |
| Crown Street Events Ltd | Hospitality | 2024 |
| Cruz Sports Coaching Limited | Arts & recreation | 2015 |
| Crypvault Holdings Limited | Financial services | 2024 |
| Crystal Clear Auto Ltd | Administrative & support | 2018 |
| Crystal Vision Limited | Professional & scientific | 2025 |
| CS Crucial Ltd | Transport & logistics | 2024 |
| CS Mechanical Services Limited | Professional & scientific | 2020 |
| CSP Electrical Contractors Ltd | Construction | 2023 |
| CT Global Holdings LLP | | 2016 |
| Ctac Services Limited | Health & social care | 2021 |
| CUB Enterprise Limited | Real estate | 2021 |
| Cuffley Car Boot Sales Limited | Wholesale & retail | 2018 |
| Cultivating Therapeutic Counselling Ltd | Professional & scientific | 2024 |
| Culver Contracts Limited | Construction | 2014 |
| Culver Group Limited | Construction | 2019 |
| Cureo Wizard Ltd | Other services | 2021 |
| Curious BOY Production Limited | Information & communication | 2024 |
| Curious Shepherd Ltd | Health & social care | 2012 |
| Curvex Business Solutions Ltd | Administrative & support | 2025 |
| Customised Unique Ltd | Construction | 2022 |