| Claybury Tenants Management Limited | Households | 2020 |
| Clean Immaculate Services Ltd | Manufacturing | 2023 |
| Clean London Services Ltd | Administrative & support | 2023 |
| Cleanbrand Ltd | Information & communication | 2019 |
| Cleaning 4UK Ltd | Administrative & support | 2025 |
| Cleaningz Ltd | Administrative & support | 2024 |
| Clear CUT Trees Ltd | Agriculture & fishing | 2012 |
| Clear House Accountants Ltd | Professional & scientific | 2013 |
| Clear World Water Technology Ltd. | Administrative & support | 2008 |
| Clearoot Ltd | Administrative & support | 2022 |
| Clef Chain Holding Limited | Information & communication | 2018 |
| Cleo Wold Ltd | Information & communication | 2023 |
| Clifford and Perkins Limited | Professional & scientific | 2024 |
| Cliffordco Ltd | Hospitality | 2019 |
| Clifton Properties Limited | Real estate | 2016 |
| Climb Build Limited | Professional & scientific | 2022 |
| Clinic 103 Ltd | Other services | 2025 |
| Cliniq C.I.C. | Health & social care | 2014 |
| CLL Scenery Limited | Construction | 2024 |
| Clones Ltd | Wholesale & retail | 2025 |
| Cloud 9 Data Consultancy Limited | Administrative & support | 2022 |
| Cloud Centrica Ltd | Information & communication | 2019 |
| Cloud Mountain Tech Ltd | Information & communication | 2024 |
| Clove Leaf Limited | Hospitality | 2012 |
| Cloverleaf Initiatives Limited | Hospitality | 2006 |
| Club 10 Ltd | Other services | 2021 |
| Club MB Holdings Limited | Professional & scientific | 2012 |
| Club MB Property Estates Limited | Real estate | 2012 |
| Clubbed 349 FPR Limited | Construction | 2024 |
| Clubbed 54 Kilmaine Road Limited | Construction | 2024 |
| Clubbed Developments Limited | Construction | 2025 |
| Clubbed Group Limited | Construction | 2024 |
| Clubbed Management Limited | Real estate | 2025 |
| Clubbed Offord Road Limited | Construction | 2025 |
| Clubbed Petley Road Limited | Construction | 2025 |
| Clubbed Sinclair Road Limited | Construction | 2025 |
| Clubbed Uxbridge Road Ltd | Construction | 2025 |
| Clubhouse Competitions Group Limited | Wholesale & retail | 2021 |
| Clyde Property Investments Limited | Construction | 1996 |
| CM Direct Services Limited | Other services | 2015 |
| CM School London Limited | Education | 2025 |
| CMP Solutions Ltd | Administrative & support | 2022 |
| CMT Builder Limited | Construction | 2020 |
| CNE Refurbishments Ltd | Construction | 2013 |
| CNR Store Ltd | Wholesale & retail | 2025 |
| Coach House Interiors Limited | Wholesale & retail | 2008 |
| Coastal Short Stays Ltd | Real estate | 2023 |
| Cobham Design Limited | Professional & scientific | 2022 |
| Cobra Inc Limited | Wholesale & retail | 2025 |
| Cobra Services Limited | Extraterritorial | 2020 |
| Coburn Trading Ltd | Wholesale & retail | 2010 |
| Coco Labelle Ltd | Manufacturing | 2014 |
| COD Hyde Limited | Construction | 2013 |
| Codigits Limited | Information & communication | 2021 |
| Coey Software Limited | Information & communication | 2020 |
| Cogent Estate Planning Limited | Other services | 2023 |
| Cogent Finance Ltd | Financial services | 2014 |
| Cogent Financial Services Limited | Financial services | 2003 |
| Cognitus Partners Limited | Information & communication | 2025 |
| Cognolite Ltd | Information & communication | 2026 |
| Coingb Ltd | Information & communication | 2019 |
| Coinhour Property Management Limited | Administrative & support | 2002 |
| Colby Developments Limited | Construction | 2017 |
| Colby Mews Limited | Construction | 2021 |
| Colchester Estates Ltd | Real estate | 2022 |
| Colchester Group Company Limited | Real estate | 2021 |
| Cole Collaborations Ltd | Professional & scientific | 2020 |
| Colebrooke Management Limited | Extraterritorial | 1996 |
| Colemans Development Limited | Construction | 2004 |
| Colhazel Ltd | Real estate | 2018 |
| Colin Buckle & Co. LLP | | 2006 |
| Colindale Skylight Limited | Real estate | 2025 |
| Colindale Yards Ltd | Real estate | 2024 |
| Coliseum Court Limited | Households | 1993 |
| Collaborate Design Ltd | Professional & scientific | 2015 |
| Collaborative Arts C.I.C. | Arts & recreation | 2023 |
| Collectors Cars & Bikes Ltd | Wholesale & retail | 2015 |
| College Sense Ltd | Information & communication | 2017 |
| Collider Nominees Ltd | Administrative & support | 2012 |
| Collingwood Court Freehold Ltd | Households | 2013 |
| Collingwood School Limited | Education | 2019 |
| Colombo Digital Ltd | Other services | 2026 |
| Colour Workshop Limited | Other services | 2026 |
| Colourize Limited | Information & communication | 2005 |
| Colpart Ltd | Administrative & support | 2005 |
| Colpart Services Limited | Administrative & support | 2020 |
| Combermere Lease Ltd | Real estate | 2022 |
| Combermere YM Limited | Real estate | 2021 |
| Comfy Home Care Ltd | Transport & logistics | 2023 |
| Comlaw Secretaries Limited | Professional & scientific | 1985 |
| Commercelia Ltd | Wholesale & retail | 2020 |
| Commercial Property Group Limited | Real estate | 2026 |
| Communication Coach and Development Ltd | Professional & scientific | 2022 |
| Communications Global Limited | Professional & scientific | 2014 |
| Compacct Limited | Information & communication | 1999 |
| Compaction Technology (Soil) Limited | Construction | 1988 |
| Company Development Limited | Professional & scientific | 2001 |
| Compass Living Ltd | Real estate | 2024 |
| Compass Residential Limited | Administrative & support | 2017 |
| Compfin Compliance Consultancy Limited | Professional & scientific | 2015 |