| Construction Union Ltd | Construction | 2019 |
| Construction Waste Services Limited | Water & waste | 2022 |
| Constructive Enterprises Holdings Ltd | Financial services | 2018 |
| Constructive Enterprises Limited | Construction | 2013 |
| Consult Adel Limited | Information & communication | 2018 |
| Consult AI Ltd | Real estate | 2025 |
| Consult and Solve Limited | Hospitality | 2018 |
| Consult Corp Ltd | Professional & scientific | 2024 |
| Consult Energy Holdings Ltd | Administrative & support | 2021 |
| Consult KFM Ltd | Information & communication | 2025 |
| Consult Plex Integration Limited | Information & communication | 2025 |
| Consult Recruitment Ltd | Administrative & support | 2022 |
| Consulta Juris (UK) Limited | Administrative & support | 2013 |
| Consultancy Tech Ltd | Professional & scientific | 2021 |
| Consultant HSS Ltd | Professional & scientific | 2020 |
| Consultant Radiologist UK Ltd | Health & social care | 2022 |
| Consultant Sync Limited | Wholesale & retail | 2023 |
| Consultants of Time Ltd | Wholesale & retail | 2024 |
| Consultark Ltd | Professional & scientific | 2022 |
| Consultation for Everyone Ltd | Administrative & support | 2023 |
| Consultify Innovations Limited | Wholesale & retail | 2024 |
| Consulting and Training Services Ltd | Information & communication | 2018 |
| Consulting Rooms 38 Limited | Other services | 2014 |
| Consulting Rooms Birmingham Limited | Other services | 2016 |
| Consulting Sphere Ltd | Wholesale & retail | 2025 |
| Consultingwerk Software Services Limited | Administrative & support | 2012 |
| Consumer Grass Limited | Other services | 2009 |
| Consumer Surplus Limited | Wholesale & retail | 2020 |
| Consummate Services Ltd | Health & social care | 2024 |
| Contabilita Ltd | Professional & scientific | 2017 |
| Contact Castings Limited | Wholesale & retail | 2012 |
| Contact Solutions (Birmingham) Limited | Transport & logistics | 2010 |
| Contact Sourcing Limited | Extraterritorial | 2010 |
| Contact Transport Limited | Transport & logistics | 1980 |
| Contacto Limited | Wholesale & retail | 1992 |
| Contag Construction Limited | Professional & scientific | 1980 |
| Container Restoration Ltd. | Extraterritorial | 1996 |
| Containers Printers (UK) Limited | Manufacturing | 1986 |
| CONTAINERS4U Limited | Transport & logistics | 2025 |
| Contek Recruitment Solutions Ltd. | Other services | 2017 |
| Contello Ltd | Manufacturing | 2015 |
| Contemporary Build Ltd | Construction | 2020 |
| Contemporary Cleaning Limited | Administrative & support | 2026 |
| Contemporary Controls Ltd | Information & communication | 1996 |
| Contemporary Cornwall Limited | Hospitality | 1999 |
| Contemporary Thoughts Press (CTP) Ltd | Information & communication | 2020 |
| Content Elevation Ltd | Information & communication | 2026 |
| Contented Casas Ltd | Real estate | 2024 |
| Contento Homes Ltd | Health & social care | 2018 |
| Contento Social Homes CIC | Health & social care | 2020 |
| Contentum (Midlands) Limited | Financial services | 2022 |
| Contesse Ltd | Administrative & support | 2021 |
| Contest a Will Today Ltd | Professional & scientific | 2023 |
| Continent Foods Limited | Wholesale & retail | 2014 |
| Continental Bitumen UK Ltd | Construction | 2020 |
| Continental Clarity Limited | Professional & scientific | 2015 |
| Continental Commerce Ltd | Other services | 2009 |
| Continental Inspection International Limited | Transport & logistics | 2019 |
| Continental Property Solutions Ltd | Real estate | 2025 |
| Continental Travel & Cargo Ltd | Transport & logistics | 2025 |
| Continuum Corporate Lawyers LLP | | 2010 |
| Contour Collective Ltd | Other services | 2025 |
| Contra Transport Ltd | Administrative & support | 2017 |
| Contract Administrator Limited | Information & communication | 2025 |
| Contract CDL Ltd | Manufacturing | 2019 |
| Contract Consulting 1988 Limited | Administrative & support | 2024 |
| Contract Geex Ltd | Professional & scientific | 2025 |
| Contract Heat Treatment Association(The) | Other services | 1978 |
| Contract Hire IT Limited | Administrative & support | 2020 |
| Contract JS Limited | Real estate | 2022 |
| Contract Leisure (Security) Limited | Professional & scientific | 2001 |
| Contract Lift UK Limited | Construction | 2013 |
| Contract Powder Coating Limited | Manufacturing | 2001 |
| Contract Supplies (White Goods) Ltd | Wholesale & retail | 2001 |
| Contractor Crowd Ltd | Administrative & support | 2019 |
| Contractor Design Limited | Professional & scientific | 1994 |
| Contractor Digs Limited | Administrative & support | 2026 |
| Contractor Relocations Ltd | Households | 2019 |
| Contracts Property Maintenance Limited | Construction | 2008 |
| Contrast Construction Limited | | 1989 |
| Contrast Facilities Management Ltd | Construction | 2021 |
| Control Capital Partners Ltd | Real estate | 2015 |
| Controlled Environment Facilities Limited | Professional & scientific | 2016 |
| Controlled Heat Treatments Limited | Financial services | 2011 |
| Controlled Maintenance (Holdings) Limited | Professional & scientific | 1995 |
| Controlled Maintenance Limited | Real estate | 1995 |
| Controlled Scaffolding Limited | Construction | 2002 |
| Contruction World Ltd | Construction | 2023 |
| Convenience Food Services Ltd | Administrative & support | 2016 |
| Convenient Homes Ltd | Hospitality | 2023 |
| Convent Property Limited | Real estate | 2018 |
| Convergence Clinics Ltd | Health & social care | 2018 |
| Convergence Realty Ltd | Real estate | 2025 |
| Conversion and Resource Evaluation Limited | Professional & scientific | 1989 |
| Convert Services Limited | Construction | 2009 |
| Convertiix Ltd | Professional & scientific | 2024 |
| Conviron Europe Ltd. | Wholesale & retail | 2002 |
| Convoy Express Ltd | Construction | 2014 |
| Conway House 136 Limited | Hospitality | 2025 |
| Conway Network Limited | Information & communication | 2017 |