| C & L Drafting Solutions Ltd. | Professional & scientific | 2017 |
| C & M Healthcare Limited | Health & social care | 2013 |
| C & M Pride Ltd | Professional & scientific | 2015 |
| C & P Curran Limited | Construction | 2022 |
| C & R Salons Ltd | Other services | 2022 |
| C H D (Winchester) Limited | Real estate | 2024 |
| C Hickman Plumbing Ltd | Construction | 2025 |
| C J Garden Services Limited | Other services | 2012 |
| C J Transport (Southern) Ltd | Transport & logistics | 2012 |
| C K Convenience Store Ltd | Wholesale & retail | 2016 |
| C&G Properties (South) Ltd | Real estate | 2025 |
| C&Jadamsbarbers Ltd | Other services | 2025 |
| C&M Gardening and Landscaping Services Ltd | Administrative & support | 2024 |
| C. Blake & Sons Limited | Wholesale & retail | 2002 |
| C. Ford Plastering Limited | Construction | 2004 |
| C.B.G. Solutions Limited | Professional & scientific | 2008 |
| C.D. & S. Residents Association Limited | Households | 1981 |
| C.L. Mathieson Limited | Hospitality | 1976 |
| C.P. and Sons Construction Ltd | Other services | 2016 |
| C.P. Architectural Limited | Professional & scientific | 2003 |
| C2 Renewable Properties Limited | Real estate | 2024 |
| Cabello Braids Ltd | Other services | 2024 |
| Cables & Coolers Ltd | Construction | 2015 |
| Cabrini ROY Ltd | Wholesale & retail | 2020 |
| Cadde LLP | | 2013 |
| Cadhay Limited | Professional & scientific | 1983 |
| Cadical Limited | Professional & scientific | 1998 |
| Cairde Ltd | Hospitality | 2023 |
| CAL Glazing Solutions Ltd | Construction | 2019 |
| Calando Limited | Wholesale & retail | 1984 |
| Calder Technical Consulting Ltd | Professional & scientific | 2022 |
| Calvert Smith and Sutcliffe Limited | Professional & scientific | 2015 |
| Camau Consulting Property Holdings Limited | Real estate | 2017 |
| Cambridge Solution and Initiatives Limited | Education | 2019 |
| Cambro Limited | Information & communication | 1997 |
| Camden Terrace Management Limited | Households | 2021 |
| Campeador Sports Management Ltd | Administrative & support | 2012 |
| Campro-Ject Limited | Other services | 2015 |
| Canary Care Global Limited | Manufacturing | 2018 |
| Candy Room Empire Limited | Wholesale & retail | 2022 |
| Candy Room Sweets Ltd | Wholesale & retail | 2017 |
| Canon Projects Ltd | Construction | 2023 |
| Canton House 2 Ltd | Hospitality | 2025 |
| Capelli Hair Limited | Real estate | 2022 |
| Capital Fleet Solutions Ltd | Financial services | 2018 |
| Captain Barry Sadler Maritime Training and Consultancy Limited | Professional & scientific | 2018 |
| Capture Accounting Ltd | Other services | 2022 |
| Carcinus Ltd | Professional & scientific | 2016 |
| Cardiac and Thoracic Surgery UK | Health & social care | 2011 |
| Care Consultancy Solutions Ltd | Professional & scientific | 2016 |
| Care Home Management Consultancy Ltd | Professional & scientific | 2022 |
| Care Home Support Limited | Administrative & support | 2019 |
| Caremeds Limited | Information & communication | 2012 |
| Careprotools Ltd | Information & communication | 2026 |
| Carerus Limited | Health & social care | 2020 |
| Carey's Property Development Ltd | Construction | 2024 |
| Carglass Windscreens Limited | Wholesale & retail | 2016 |
| Caribbean Trading Group Limited | Wholesale & retail | 2024 |
| Caribbean Trading Limited | Wholesale & retail | 1990 |
| Carlito's Group Ltd | Administrative & support | 2014 |
| Carlton Property Maintenance Limited | Construction | 2007 |
| Caromar Limited | Manufacturing | 2007 |
| Carowner Pro Ltd | Administrative & support | 2023 |
| Carpentry&Co Limited | Construction | 2019 |
| Carpevita Therapies Limited | Health & social care | 2015 |
| Carr Family Holdings Limited | Professional & scientific | 2025 |
| Carsa Holdings Limited | Wholesale & retail | 2020 |
| Carsa Limited | Wholesale & retail | 2020 |
| Carters Customs Limited | Other services | 2020 |
| Casa Amor Lets Limited | Real estate | 2023 |
| Casa M P Limited | Real estate | 2015 |
| Cash Transfer Company Limited | Financial services | 2022 |
| Cashard Limited | Real estate | 2017 |
| Caspian Leisure Ltd | Hospitality | 2022 |
| Cass Smyth Carpentry Limited | Construction | 2024 |
| Castill | Financial services | 2014 |
| Castillion Consulting Limited | Professional & scientific | 2022 |
| Castle Executive Homes Limited | Real estate | 2003 |
| Caterbox UK Limited | Administrative & support | 2012 |
| Catering Equipment Support Limited | Hospitality | 2011 |
| Cathedral Topco Limited | Administrative & support | 2023 |
| Cathedral View (Winchester) Management Limited | Households | 2015 |
| Cavendish Leisure Limited | Real estate | 2019 |
| Cavendish Menswear Limited | Wholesale & retail | 2018 |
| Cavendish Womenswear Ltd | Wholesale & retail | 2022 |
| CAZ Duthie Limited | Professional & scientific | 2022 |
| CBB Repair Ltd | Wholesale & retail | 2023 |
| Cbih Limited | Financial services | 2013 |
| CBM Accountants Limited | Professional & scientific | 2002 |
| CBM Holdings Ltd | Real estate | 2023 |
| Cbsl Limited | Professional & scientific | 2015 |
| Cc.Ecology Ltd | Professional & scientific | 2013 |
| Cccarpentry and Building Ltd | Construction | 2013 |
| CCD Properties Ltd | Real estate | 2014 |
| CCE Consulting Ltd | Professional & scientific | 2026 |
| CCM Homes (Scotland) Limited | Construction | 2005 |
| Ccoa Ltd | Real estate | 2002 |
| Ccuk Beauty Ltd | Health & social care | 2019 |
| CDM (Southern) Electrical Ltd | Manufacturing | 2026 |
| CE Barber Ltd | Other services | 2019 |