| Close Brothers Scientific Services Limited | Extraterritorial | 2017 |
| Close Capital Limited | Administrative & support | 2021 |
| Close Tech Limited | Real estate | 2018 |
| Closed Cell Sprayfoam Removal Limited | Construction | 2026 |
| Cloud Digital Media Ltd | Information & communication | 2012 |
| CLOUD9 Coffee Limited | Hospitality | 2018 |
| Cloverform Limited | Hospitality | 2001 |
| Club Human Limited | Health & social care | 2022 |
| Club Mint Limited | Other services | 2024 |
| Club Right Ltd | Information & communication | 2012 |
| CMD Steel Fabrications Ltd | Manufacturing | 2026 |
| CMH Workbook Solutions Ltd | Professional & scientific | 2024 |
| CMO Holdings Limited | Real estate | 2020 |
| CMS Wines & Spirits Limited | Wholesale & retail | 2025 |
| CN Trading INT. Ltd | Administrative & support | 2008 |
| Coastair Ltd | Information & communication | 2018 |
| Codair 2000 Limited | Professional & scientific | 1999 |
| Codair Design and Publicity Limited | Information & communication | 1986 |
| Coderise Talent Limited | Administrative & support | 2025 |
| Codestack Consulting Limited | Information & communication | 2023 |
| Coex Studios Limited | Information & communication | 2021 |
| Coins of the Realm Limited | Wholesale & retail | 2003 |
| Colette S Copping Limited | Health & social care | 2018 |
| Colin Armitage Ltd | Construction | 2019 |
| Colourbond (the Printers) Limited | Manufacturing | 2016 |
| Colourbond Design & Print Limited | Manufacturing | 2016 |
| Colours Hair Limited | Other services | 2013 |
| Colvern Electrical Limited | Construction | 2014 |
| Comfort Heating (Essex) Limited | Construction | 2026 |
| Command Fire and Security Ltd | Professional & scientific | 2017 |
| Commercial and Residential Building Surveys - (Carbs) Ltd | Professional & scientific | 2023 |
| Community Glaucoma Network Limited | Health & social care | 2015 |
| Company Property Ltd. | Households | 2014 |
| Compass Education Trust Ltd | Education | 2011 |
| Compass Impex Limited | Wholesale & retail | 1995 |
| Compass Sports Ltd | Education | 2021 |
| Complete AI Services Ltd | Information & communication | 2026 |
| Complete Asset Leadership Limited | Other services | 2010 |
| Complete Electrical & Building Services Limited | Construction | 2014 |
| Complete Insure Group UK Limited | Other services | 2024 |
| Complete Locksmith Services Ltd | Wholesale & retail | 2026 |
| Concept Management Group Ltd | Administrative & support | 2022 |
| Concept PU Limited | Wholesale & retail | 2025 |
| Coniston Freehold Limited | Other services | 2017 |
| Connect-B Limited | Information & communication | 2023 |
| Conrad Jacob Ltd | Professional & scientific | 2009 |
| Construction 6 Two Ltd | Construction | 2026 |
| Construction Courses Direct Ltd | Education | 2019 |
| Construction Services DT Limited | Construction | 2014 |
| Construction Support Service Limited | Construction | 2014 |
| Construction Training & Consultancy Services Ltd | Education | 2019 |
| Consulting Capital Limited | Professional & scientific | 2022 |
| Consulting Logistics Limited | Professional & scientific | 2009 |
| Contract Salvage Solutions Ltd | Wholesale & retail | 2026 |
| Contract Security Maintenance Limited | Administrative & support | 2004 |
| Contrakt Limited | Construction | 2000 |
| Cookie TCG Ltd | Wholesale & retail | 2024 |
| Cooks GAS and Plumbing Solutions Limited | Construction | 2018 |
| Cool and Hot Ltd. | Wholesale & retail | 2014 |
| Cooleo Properties Ltd | Real estate | 2022 |
| Cooper Drive Management Company Ltd | Professional & scientific | 2013 |
| Coopercrayfourd Office Environments Limited | Manufacturing | 2007 |
| Copperfield Bakeries Limited | Hospitality | 2008 |
| Core and Calm Ltd | Arts & recreation | 2024 |
| Core Supply Group Limited | Administrative & support | 2015 |
| Coredata Consulting Services Ltd | Information & communication | 2025 |
| Coredefense Limited | Information & communication | 2024 |
| Cornell Property Holdings Limited | Households | 2021 |
| Corner Club Canvey Limited | Hospitality | 2010 |
| Cornerstone Interiors Ltd | Administrative & support | 2000 |
| Cornerstone Psychological Services Limited | Health & social care | 2017 |
| Cornsland Limited | Households | 1996 |
| Cornwell Consulting Limited | Professional & scientific | 2023 |
| Coronation Roofing & Building Limited | Construction | 2008 |
| Cosmetic Courses Holdings Limited | Financial services | 2024 |
| Cosmetic Courses International Limited | Other services | 2017 |
| Cosmetic Courses Limited | Other services | 2013 |
| Cosmic Elephant Limited | Health & social care | 2023 |
| Cosmo.Recruit Ltd | Administrative & support | 2023 |
| Cosy Campervans Limited | Administrative & support | 2010 |
| Could U B Ltd | Arts & recreation | 2022 |
| Counter Surveillance Group Limited | Administrative & support | 2025 |
| Countryside Refurb Ltd | Wholesale & retail | 1996 |
| County Design Landscapes Ltd | Administrative & support | 2026 |
| Countywide Decor Limited | Construction | 2009 |
| Courtace Limited | Real estate | 1993 |
| Courtdelta Limited | Wholesale & retail | 1995 |
| Coverdale K9 Security Services Limited | Other services | 2005 |
| Covo Homes Ltd | Real estate | 2016 |
| CPH Printing Services Ltd | Professional & scientific | 2022 |
| CPM Communications Limited | Information & communication | 2011 |
| CPN Trading Ltd | Real estate | 2017 |
| CPP Trading Ltd | Professional & scientific | 2018 |
| CPS Trading Ltd | Real estate | 2017 |
| Craft Cables Ltd | Construction | 2026 |
| Craftymack's Gifts Ltd | Manufacturing | 2023 |
| Cranfield Industrial Services Limited | Administrative & support | 2003 |
| Crayfish Joinery Ltd | Manufacturing | 2020 |
| Crays Hall Trading Limited | Wholesale & retail | 2011 |
| Craythus Limited | Hospitality | 2008 |