| Confitex UK Limited | Manufacturing | 2017 |
| Congruent Solutions UK Limited | Information & communication | 2008 |
| Coniston Crescent Ltd | Real estate | 2014 |
| Conn-Selmer Europe Limited | Wholesale & retail | 1978 |
| Connaught Cars Limited | Wholesale & retail | 2019 |
| Connaught House (Slough) Limited | Construction | 2018 |
| Connaught Leasing Limited | Wholesale & retail | 1996 |
| Connect A.B. Limited | Administrative & support | 1994 |
| Connect Automotive Ltd | Wholesale & retail | 2025 |
| Connect Home Care Ltd | Health & social care | 2023 |
| Connect Learning London Ltd | Education | 2020 |
| Connect Recruitment Consultants Limited | Administrative & support | 1987 |
| Connecteco Developments Ltd | Construction | 2024 |
| Connectra Solutions Ltd | Professional & scientific | 2026 |
| Connekt Ltd | Administrative & support | 2024 |
| Conney Ltd | Administrative & support | 2025 |
| Connoisseur Cuisines Limited | Hospitality | 2025 |
| Conoscen Limited | Information & communication | 2022 |
| Conovo Ltd | Information & communication | 2020 |
| Conposita Ltd | Professional & scientific | 2021 |
| Cons Services Ltd | Administrative & support | 2016 |
| Consolidate Services Ltd | Construction | 2017 |
| Consort House (Fleet) Limited | Construction | 2015 |
| Constant Cooled Limited | Other services | 2012 |
| Constant Transport Solutions Ltd | Transport & logistics | 2024 |
| Constantino Services Ltd | Administrative & support | 2019 |
| Constellium UK Limited | Wholesale & retail | 1927 |
| Construction Equipment Services Limited | Administrative & support | 2003 |
| Construction Equipment Supplies Ltd | Administrative & support | 2016 |
| Construction Machines Sales Ltd | Wholesale & retail | 2015 |
| Construction View Technologies Ltd | Information & communication | 2022 |
| Constructiononline Limited | Education | 2025 |
| Consuelo Lagarto Services Limited | Wholesale & retail | 2018 |
| Consult Edge Limited | Professional & scientific | 2014 |
| Consult ME (UK) Ltd | Professional & scientific | 2005 |
| CONSULT4 Associates Ltd | Professional & scientific | 2019 |
| Consulting Concepts Ltd | Administrative & support | 2015 |
| Consulting Holdco Limited | Professional & scientific | 2026 |
| Consultix Ltd | Professional & scientific | 2017 |
| Consultree Ltd | Administrative & support | 2014 |
| Contact Management Ltd | Other services | 2012 |
| Contact to Contract Limited | Professional & scientific | 1998 |
| Conteco Group Limited | Real estate | 2023 |
| Conteco Living Limited | Real estate | 2023 |
| Content by Rico Ltd | Information & communication | 2026 |
| Contenthost Limited | Information & communication | 2018 |
| Continental Chauffeur Services London Limited | Transport & logistics | 2017 |
| Continental Consultancy Ltd. | Information & communication | 2020 |
| Continental Removal & Storage Limited | Transport & logistics | 2021 |
| Continental Tyre Group Ltd. | Wholesale & retail | 1935 |
| Continental U.K. Group Holdings Limited | Professional & scientific | 1956 |
| Contractors Umbrella Services Ltd | Other services | 2018 |
| Contractsonline Ltd | Professional & scientific | 2005 |
| Contrarian Limited | Extraterritorial | 1999 |
| Controls Solutions Ltd | Wholesale & retail | 2022 |
| Contronix Ltd | Professional & scientific | 2024 |
| Convenience at Local Ltd | Wholesale & retail | 2023 |
| Convey Properties Limited | Real estate | 2025 |
| Conway Investment Properties Ltd | Real estate | 2015 |
| Conway’S Coffee House Ltd | Hospitality | 2015 |
| Coogan London Limited | Wholesale & retail | 2011 |
| Cook and POP Limited | Professional & scientific | 2020 |
| Cook to Surf Limited | Transport & logistics | 2022 |
| Cookham Road (Maidenhead) Limited | Administrative & support | 1983 |
| Cookie Coach Company (UK) Limited(The) | | 1982 |
| Cookie JAR London Ltd | Hospitality | 2020 |
| Cookie Skills Ltd | Professional & scientific | 2019 |
| Cool TEC Shopfitters Limited | Manufacturing | 2014 |
| Coolplanet Ltd | Construction | 2022 |
| Coolref Service Ltd | Energy | 2025 |
| Cooper Pensions Limited | Professional & scientific | 1992 |
| Coopertec Systems Limited | Professional & scientific | 1990 |
| Copperfields Residents Association (Mirador) Limited | Households | 1998 |
| Coral Software Ltd | Information & communication | 2025 |
| Core Communication Holdings Limited | Professional & scientific | 2017 |
| Core Communication Retail Limited | Information & communication | 2012 |
| Core Communication Services Limited | Financial services | 2005 |
| Core Consulting Ltd | Administrative & support | 2022 |
| Core Goods Ltd | Wholesale & retail | 2026 |
| Core Healthcare Ltd | Administrative & support | 2021 |
| Core Illumination Healing Ltd | Health & social care | 2012 |
| Core IO Ltd | Wholesale & retail | 2020 |
| Core Network Solutions UK Ltd | Information & communication | 2015 |
| Coreaxia Solutions Ltd | Wholesale & retail | 2024 |
| Corecraft Solutions Ltd | Construction | 2025 |
| Coremet Limited | Administrative & support | 2018 |
| Coresoft Solutions Limited | Information & communication | 2016 |
| Cornerpoint Limited | Real estate | 2026 |
| Cornerstone Intelligence Ltd | Information & communication | 2026 |
| Cornerstone London Property Ltd | Households | 2025 |
| Cornerstone Motors Ltd | Wholesale & retail | 2026 |
| Cornerstone Properties Limited | Construction | 1997 |
| Corpaul Associates Limited | Construction | 2016 |
| Corpskies Ltd | Information & communication | 2019 |
| Corvus Management Group Ltd | Information & communication | 2021 |
| Cosi Carpets (Ashford) Ltd | Construction | 2023 |
| Cosi Carpets (Radlett) Ltd | Wholesale & retail | 2023 |
| Cosi Carpets Ltd | Wholesale & retail | 2012 |
| Cosi Carpets Slough Ltd | Wholesale & retail | 2025 |
| Cosi Group Ltd | Real estate | 2019 |