| Circlegrouptech Ltd | Education | 2021 |
| City Light System Ltd | Energy | 2019 |
| Citycover Limited | Households | 1982 |
| Citygate Builders Limited | Wholesale & retail | 2000 |
| Citygate Leasing Limited | Administrative & support | 2024 |
| Cityline Builders & Decorators Limited | Construction | 2026 |
| Citystay Management Ltd | Hospitality | 2026 |
| Civic Digital UK Ltd | Information & communication | 2026 |
| CJ Digital Art Limited | Professional & scientific | 1998 |
| CJ Scenery Limited | Construction | 2017 |
| CJH Property Holdings Ltd | Real estate | 2024 |
| CK BGD Group Limited | Information & communication | 2016 |
| Ckks Services Limited | Information & communication | 2008 |
| Claddassist Ltd | Construction | 2019 |
| Cladern Ltd | Professional & scientific | 2008 |
| Claire Bannister Cares Limited | Other services | 2025 |
| Clapham Mansions Freehold Limited | Households | 2004 |
| Clarendon Court (London) Freehold Limited | Households | 2000 |
| Claygate Groundworks Ltd | Professional & scientific | 2021 |
| Clayton Ridgeway Limited | Construction | 2016 |
| Clean & Tidy London Ltd | Administrative & support | 2011 |
| Clean Masters London Ltd | Administrative & support | 2025 |
| Clear Thoughts Therapy Ltd | Professional & scientific | 2020 |
| Clearbridge Housing Limited | Hospitality | 2023 |
| Clearview@Property@ Commercial Ltd | Real estate | 2026 |
| Clemence Richard Limited | Wholesale & retail | 2004 |
| Clippers FS Limited | Other services | 2024 |
| Clipston Construction Control Limited | Professional & scientific | 1991 |
| Clipston Project Management Limited | Construction | 1999 |
| Cloisters Self Management of Hemel Hempstead Limited | Real estate | 2012 |
| Clos Bibliotheque UK Ltd | Wholesale & retail | 2024 |
| Cloudwd Solutions Ltd | Information & communication | 2024 |
| Cloudyland Ltd | Wholesale & retail | 2025 |
| Club Chauffeurs Ltd | Transport & logistics | 2019 |
| Clucks Peri Peri Limited | Hospitality | 2025 |
| Clyfford Consultants Ltd | Administrative & support | 2018 |
| Clyne Communications Limited | Financial services | 2002 |
| Cmax Accountancy Services Limited | Professional & scientific | 2014 |
| CMD Software Ltd | Information & communication | 2023 |
| CMF Technology Limited | Information & communication | 2016 |
| CNA Construction Limited | Water & waste | 2023 |
| CNC Dave Limited | Manufacturing | 2026 |
| Cncd Limited | Wholesale & retail | 2015 |
| CNF Plastering Ltd | Construction | 2025 |
| Co-Create HER Limited | Education | 2024 |
| Code Brew Labs Limited | Information & communication | 2019 |
| Code London Ltd | Information & communication | 2014 |
| Codebee Limited | Information & communication | 2014 |
| Coffee Kraft Ltd | Wholesale & retail | 2023 |
| Coffee Marketing Digital Ltd | Professional & scientific | 2025 |
| Cole Enterprises Limited | Other services | 1987 |
| Cole Services Limited | Administrative & support | 2006 |
| Coles Brothers Ltd | Wholesale & retail | 2018 |
| College Company Services Limited | Extraterritorial | 2019 |
| Collins Sarwar Estates Ltd | Real estate | 2012 |
| Colorchem Co., Ltd | Extraterritorial | 2016 |
| Colour Palette by Tassy Ltd | Other services | 2022 |
| Colt Transport Ltd | Water & waste | 2022 |
| Comfy Services Ltd | Other services | 2022 |
| Commercial Charcoal UK Ltd | Manufacturing | 2025 |
| Commercial Interior Blinds Ltd | Manufacturing | 2022 |
| Commercial Trading & Engineering Ltd | Water & waste | 2023 |
| Commoditrading Ltd | Wholesale & retail | 2025 |
| Community Coding Club Limited | Information & communication | 2018 |
| Compass Carpentry Limited | Construction | 2023 |
| Compass London Ltd | Professional & scientific | 2022 |
| Compass Property Sales and Lettings Limited | Real estate | 2023 |
| Complete Construction Developments Limited | Construction | 2013 |
| Complete Office Search Ltd | Real estate | 2008 |
| Concert Piano Services Ltd | Arts & recreation | 2025 |
| Connected to Construction Ltd | Construction | 2019 |
| Conneely Group Ltd | Administrative & support | 2023 |
| Consigned Sealed Delivered Ltd | Wholesale & retail | 2020 |
| Constabulary Close (West Drayton) Freeholders 2 Limited | Real estate | 2020 |
| Constantin DD Ltd | Transport & logistics | 2023 |
| Contemporary View Consulting Limited | Education | 2012 |
| Control Freaks AV Ltd | Professional & scientific | 2021 |
| Cooley Metals Co., Ltd. | Administrative & support | 2023 |
| Copperhead Editions Limited | Arts & recreation | 2013 |
| Copperhead Electric Ltd | Construction | 2013 |
| COR Noir Developments Limited | Construction | 2026 |
| Corcoran and MAY (UK) Limited | Wholesale & retail | 2009 |
| Corinne O'Donnell Presentation Design Ltd | Arts & recreation | 2013 |
| Cornhill Construction Ltd | Construction | 2018 |
| Cosima Health | Health & social care | 2026 |
| Cosmetiques Argana Ltd | Manufacturing | 2020 |
| Costirom Renovations Limited | Construction | 2017 |
| Cosy Spot Ltd | Hospitality | 2021 |
| Count-Lite Limited | Professional & scientific | 2026 |
| Country House Furniture Ltd | Wholesale & retail | 2021 |
| Countrywide Wills & Estate Planning (Stamford) Ltd | Professional & scientific | 2019 |
| Countrywide Wills & Estate Planning (Uttoxeter) Ltd | Professional & scientific | 2019 |
| Countrywide Wills & Estate Planning Ltd | Professional & scientific | 2019 |
| County Architectural Aluminium Limited | Construction | 1991 |
| County Block Paving & Surfacing Ltd | Construction | 2020 |
| County Roadways Limited | Construction | 2008 |
| Covent Garden Chamber Orchestra Limited | Arts & recreation | 2017 |
| Covent Global AI Limited | Information & communication | 2024 |
| Coyle Haulage Limited | Transport & logistics | 2006 |
| Coyle Properties Limited | Construction | 2016 |