| Clacks Limited | Construction | 2007 |
| Clarence House (Kent) Limited | Real estate | 2016 |
| Classic Rock Tours (UK) Limited | Administrative & support | 2011 |
| Cleaning & Maintenance London Ltd | Administrative & support | 2020 |
| Clearglass Insights Ltd | Information & communication | 2024 |
| Clearpath Automation Ltd | Professional & scientific | 2026 |
| Click Ethical Ltd | Professional & scientific | 2020 |
| Climacon Solutions Ltd | Construction | 2022 |
| Clinical Films Ltd | Information & communication | 2012 |
| Clitheroe Property Ltd | Real estate | 2020 |
| Cloud DB Ltd | Information & communication | 2019 |
| CM Group Holdings Limited | Other services | 2017 |
| Cm&C Solutions Limited | Wholesale & retail | 2023 |
| CMH Tennis Ltd | Arts & recreation | 2023 |
| CMS Cooling Ltd | Administrative & support | 2019 |
| Cnoc Hotel Limited | Hospitality | 2021 |
| Co Waste Ltd | Water & waste | 2024 |
| Co-Pang Corporate Services Limited | Health & social care | 2014 |
| Cobham Marquees Limited | Administrative & support | 2019 |
| Cobra Carpentry Limited | Construction | 2020 |
| Cockburn Holdings Ltd | Financial services | 2017 |
| Coffee BOY Limited | Hospitality | 2014 |
| Cole's Salons Ltd | Other services | 2010 |
| Collectvinyl Ltd | Wholesale & retail | 2025 |
| College Road (Hextable) Management Company Limited | Households | 2003 |
| Colonna International Ltd | Professional & scientific | 2015 |
| Coloría Ltd | Construction | 2025 |
| Colour Cases Ltd | Wholesale & retail | 2022 |
| Colour Cosmetics Ltd | Wholesale & retail | 2019 |
| Colour Scene Ltd | Information & communication | 2023 |
| Colvan Ltd. | Construction | 2018 |
| Come to My Church Ltd | Wholesale & retail | 2019 |
| Comodex UK Ltd | Wholesale & retail | 2014 |
| Complete Clean Services UK Ltd | Administrative & support | 2017 |
| Complete Doorset Solutions Install Ltd | Manufacturing | 2022 |
| Complete Homeworks Limited | Construction | 2004 |
| Complete Maintenance Services U.K. Ltd | Administrative & support | 2019 |
| Condition Perform Ltd | Health & social care | 2012 |
| Condor Trade Limited | Administrative & support | 1999 |
| Conic Fire Safety Ltd | Public administration | 2022 |
| Connaught Capital Advisors Limited | Other services | 2018 |
| Connected-Uk.Com LLP | | 2002 |
| Conrad Ruffoni Limited | Professional & scientific | 2003 |
| Construction Specialist Training Limited | Education | 2024 |
| Consult Solition Ltd | Wholesale & retail | 2022 |
| Coolest Cooling Ltd | Construction | 2025 |
| Copang-Plus Ventures Limited | Real estate | 2020 |
| Copek Limited | Construction | 2018 |
| Copley & Co Projects Ltd | Construction | 2024 |
| Copley 5 Ltd | Financial services | 2021 |
| Copley Consultancy Ltd | Extraterritorial | 2024 |
| Copley Infrastructure Ltd | Construction | 2021 |
| Copley Investments Limited | Real estate | 2021 |
| Copley Limited | Construction | 2008 |
| Corbico Limited | Hospitality | 1985 |
| Cordery Castle Limited | Professional & scientific | 2007 |
| Core 4 Life Ltd | Health & social care | 2020 |
| Coriander Investment Club LLP | | 2026 |
| Cornwall Skip Hire Ltd | Water & waste | 2026 |
| Corporate Counsel Ltd | Professional & scientific | 2013 |
| Coshall Property Associates Limited | Real estate | 2023 |
| Cosy Home CGC Ltd | Real estate | 2024 |
| Cosy Home Developments Ltd | Construction | 2014 |
| Cosyseal (Double Glazing) Limited | Other services | 2000 |
| Cosyseal Windows Limited | Construction | 2004 |
| Cottage Day Ltd | Health & social care | 2012 |
| Countdown Services (Kent) Limited | Transport & logistics | 2013 |
| Country View Residents Association Limited | Households | 1991 |
| Courts Air Conditioning Limited | Energy | 2012 |
| Coventry Road Property Investments Ltd | Real estate | 2023 |
| Cowboy Grill Limited | Hospitality | 2026 |
| Craft T Cake Limited | Hospitality | 2017 |
| Craig Baker Plastering Limited | Construction | 2023 |
| Cranstone Court Management Limited | Households | 1991 |
| Cray Mill Leisure Limited | Construction | 2012 |
| Creating Digital Ltd | Information & communication | 2013 |
| Creative Collab Agency LLP | | 2021 |
| Creative Vanity Ltd | Professional & scientific | 2023 |
| Crescent Court Residents Association (Sidcup) Limited | Households | 1968 |
| Crescit International Limited | Administrative & support | 2025 |
| Crestview Global Limited | Real estate | 2025 |
| Crispy Capital Limited | Construction | 2014 |
| Cristal Investment Limited | Real estate | 2024 |
| Crofton Electrical Services Limited | Construction | 2001 |
| Crosskey Edinburgh Ltd | Construction | 2021 |
| Cruze Candle Company Ltd | Manufacturing | 2023 |
| CS Trade Training Ltd | Education | 2025 |
| CSP Medical Limited | Health & social care | 2016 |
| CST Construction Services Ltd | Construction | 2019 |
| CST Training Ltd | Education | 2019 |
| CST Web Tools Ltd | Information & communication | 2026 |
| CT Property Investments Limited | Real estate | 2010 |
| Ctax Limited | Professional & scientific | 2018 |
| CTP Contractors Limited | Construction | 2013 |
| Culverton Sidcup Management Company Limited | Households | 1981 |
| Cuore Food From the Earth Ltd | Hospitality | 2015 |
| Currency Consulting Ltd | Information & communication | 2023 |
| Cutler Freight Forwarding Limited | Transport & logistics | 1982 |
| Cygnus Holding Services LLP | | 2025 |
| Cypry Pool Fishery Limited | Arts & recreation | 2013 |