| Circa 1 Media Limited | Arts & recreation | 2006 |
| Circle Electromechanical Limited | Professional & scientific | 2024 |
| Circular Way Limited | Wholesale & retail | 2007 |
| Citadel Building Company Ltd | Construction | 2012 |
| City Conversion Ltd | Construction | 2014 |
| City Electrical Limited | Construction | 2016 |
| Citydrop Logistics Ltd | Transport & logistics | 2026 |
| Cjpk Enterprises Limited | Information & communication | 2003 |
| CK Virdi Ltd | Health & social care | 2026 |
| Ckrit Labs Ltd | Information & communication | 2026 |
| Clapham Rios Limited | Hospitality | 2026 |
| Classic Tech Limited | Information & communication | 2026 |
| Claudia Rossi Trading UK Limited | Wholesale & retail | 2021 |
| Claughton Estates Limited | Construction | 2022 |
| Clayton Precision Engineering Co. Ltd. | Manufacturing | 1999 |
| Clean and Care PM Ltd | Administrative & support | 2025 |
| Clear ARC Consulting Limited | Professional & scientific | 2021 |
| Clearoffices Ltd | Administrative & support | 2017 |
| Cleo Matlou Ltd | Other services | 2018 |
| Click Construction Limited | Construction | 2014 |
| Clinixall Limited | Health & social care | 2023 |
| Clinmon Ltd | Professional & scientific | 2021 |
| Cloudness Ltd | Information & communication | 2019 |
| Clover Leaf (London) Ltd | Real estate | 2026 |
| Cmcps Ltd | Construction | 2008 |
| CMI Group Limited | Arts & recreation | 2002 |
| CN85 Ltd | Real estate | 2023 |
| Co Palette Ltd | Hospitality | 2024 |
| Co&C Services Ltd | Construction | 2024 |
| Cobham Estates Limited | Real estate | 2024 |
| Cocoon Hair & Beauty Isleworth Ltd | Other services | 2012 |
| COD and Chips Ltd | Hospitality | 2016 |
| Code 2 Conquer Limited | Information & communication | 2026 |
| Coded Media Ltd | Information & communication | 2015 |
| Codenexus Ltd | Information & communication | 2023 |
| Coeus HQ Limited | Arts & recreation | 2021 |
| Coker & Sons Construction Ltd | Real estate | 2025 |
| Colabah Ltd | Wholesale & retail | 2025 |
| Colbert Capital Partners Ltd | Other services | 2020 |
| Coldsteam GIN Limited | Manufacturing | 2022 |
| Collab Consultancy Limited | Professional & scientific | 2023 |
| Collata Limited | Information & communication | 2018 |
| Collectio Ltd | Administrative & support | 2026 |
| Colliers Launches Thames Boat Hire Limited | Transport & logistics | 2014 |
| Coln Property Limited | Real estate | 2026 |
| Coltsfoot Legal Services Limited | Professional & scientific | 2020 |
| Combined International Harvesters Limited | | 1986 |
| Comcast Capital International Limited | Professional & scientific | 2020 |
| Comcast Funding Co 1 Limited | Financial services | 2026 |
| Comcast Funding Co 2 Limited | Financial services | 2026 |
| Comincia Limited | Administrative & support | 2013 |
| Commando Active Ltd | Arts & recreation | 2014 |
| Commented Ltd | Information & communication | 2023 |
| Complete Haven Limited | Hospitality | 2026 |
| Complete Refinish Ltd | Construction | 2015 |
| Concept Bespoke Interiors Limited | Construction | 2005 |
| Concept Bespoke Interiors Trustee Company Limited | Administrative & support | 2021 |
| Concept Trading & Distribution (UK) Ltd | Wholesale & retail | 2001 |
| Conceptual Build Limited | Construction | 2017 |
| Condos Realty Services Limited | Administrative & support | 2024 |
| Connecting the Spectrum Ltd | Extraterritorial | 2016 |
| Consilium Advisory & Management Consulting Limited | Extraterritorial | 2018 |
| Constance Solutions Limited | Professional & scientific | 2013 |
| Construction Delivery Ltd | Construction | 2020 |
| Construction JTW Limited | Construction | 2025 |
| Consult in SIM Ltd | Information & communication | 2013 |
| Consulting Surge Limited | Health & social care | 2013 |
| Contego Incorporated Ltd | Financial services | 2014 |
| Contract Waste Management Limited | Water & waste | 2022 |
| Convert Elite Traders Ltd | Construction | 2023 |
| Conway Lighting Limited | Arts & recreation | 2016 |
| Coogan Constructions Limited | Construction | 2022 |
| Cool Cats Cycling Ltd | Manufacturing | 2024 |
| Cooling Mechanical Ltd | Energy | 2018 |
| Cooltura Limited | Information & communication | 2007 |
| COOLTURA24 Ltd | Information & communication | 2017 |
| Copenhagen 2RE Limited | Real estate | 2024 |
| Coral Management Limited | Wholesale & retail | 2005 |
| Coral Shore Properties UK Ltd | Real estate | 2019 |
| Corecraft Ltd | Construction | 2023 |
| Corevia Global Solutions Ltd | Professional & scientific | 2025 |
| Corner Superstore Limited | Other services | 2020 |
| Coronation 860 Ltd | Transport & logistics | 2023 |
| Corporate Investors International (UK) Ltd | Real estate | 2025 |
| Cosycanvasuk Ltd | Wholesale & retail | 2025 |
| Cotovanu George Construction Ltd | Construction | 2019 |
| Cottage Brew (London) Limited | Hospitality | 2019 |
| Cottage Housing Ltd | Real estate | 2022 |
| Cotton and Cotton Waste Ltd | Wholesale & retail | 2012 |
| Coval Investments Ltd | Real estate | 2022 |
| Coverspace Group Limited | Information & communication | 2023 |
| COZ Transport Ltd | Transport & logistics | 2012 |
| Craft Masters Carpentry Ltd | Manufacturing | 2024 |
| Craig Value Consultng Ltd | Professional & scientific | 2024 |
| Cranmer Consultants Ltd | Information & communication | 2026 |
| Crawley Autofit Limited | Wholesale & retail | 2005 |
| Crazy Frog Ltd | Administrative & support | 2022 |
| Creanovate Ltd | Professional & scientific | 2016 |
| Creative Arch Ltd | Professional & scientific | 2015 |
| Creative Aspirations Ltd. | Information & communication | 2012 |