| Castle Body Works Limited | Wholesale & retail | 1982 |
| Castle Captures Ltd | Professional & scientific | 2024 |
| Castle Coins Ltd | Wholesale & retail | 2026 |
| Castle Fields (Portchester) Limited | Administrative & support | 2002 |
| Castle Fire Protection Limited | Construction | 2008 |
| Castle Flooring Services Ltd | Wholesale & retail | 2019 |
| Castle Vale Specsavers Limited | Wholesale & retail | 2018 |
| Castle Valeting Limited | Administrative & support | 2025 |
| Castle Venture Holdings Limited | Financial services | 2020 |
| Castleacre Systems Limited | Professional & scientific | 2002 |
| Castlefranc Limited | Construction | 2003 |
| Castlepoint Specsavers Limited | Wholesale & retail | 2018 |
| Catalyst Performance Partners Ltd | Professional & scientific | 2026 |
| CATALYST7 Consulting Ltd | Professional & scientific | 2024 |
| Catcliffe Visionplus Limited | Wholesale & retail | 1999 |
| Cater Supply Ltd | Wholesale & retail | 2015 |
| Caterham Specsavers Limited | Wholesale & retail | 2005 |
| Caterham Visionplus Limited | Wholesale & retail | 2005 |
| Catford Specsavers Limited | Wholesale & retail | 2008 |
| Catford Visionplus Limited | Wholesale & retail | 2008 |
| Catherine Court Residents Association Limited | Households | 1979 |
| Catisfield Gate Management Company Limited | Other services | 2002 |
| Catisfield Holdings Limited | Real estate | 2025 |
| Catling Cleaners Limited | Administrative & support | 2022 |
| Catorix Limited | Financial services | 2012 |
| Catt Electrical Limited | Construction | 2026 |
| Catvog Domi Audiology Specsavers Limited | Wholesale & retail | 2025 |
| Catvog Domiciliary Specsavers Limited | Wholesale & retail | 2014 |
| Cavara Property Group Limited | Real estate | 2025 |
| Cavell (Southern) Limited | Professional & scientific | 2016 |
| Cavershams Wealth Limited | Administrative & support | 2021 |
| CB Electrical (Services) Ltd | Construction | 2016 |
| CBE Installations Ltd | Construction | 2008 |
| CBK Gaming Ltd | Manufacturing | 2019 |
| Cbma Limited | Construction | 2019 |
| CBS Holdings Ltd | Financial services | 2023 |
| CC Communication & Design Limited | Professional & scientific | 2015 |
| CC Freehold Limited | Households | 2020 |
| CCL Properties Limited | Real estate | 2013 |
| Ccs-Global Ltd | Professional & scientific | 2022 |
| CCT Consultancy Ltd | Professional & scientific | 2025 |
| CCW Services Limited | Construction | 2003 |
| Cdal Ltd | Professional & scientific | 2014 |
| CDC Construction Developments Limited | Construction | 2022 |
| CDH Accounts Limited | Professional & scientific | 2021 |
| CDK Plumbing Ltd | Construction | 2014 |
| CDL Managing Ltd | Real estate | 2022 |
| Cdnce Limited | Wholesale & retail | 2025 |
| CDW Finance Limited | Financial services | 2016 |
| CE Fine Wines Limited | Wholesale & retail | 2020 |
| CE Solar & Power Ltd | Construction | 2024 |
| Cedar Law Limited | Professional & scientific | 2013 |
| Cedargrove Holdings Limited | Real estate | 2020 |
| Cedargrove Property Ltd | Construction | 2019 |
| Celerico Ltd | Wholesale & retail | 2025 |
| Cellbell Ltd | Wholesale & retail | 2012 |
| Celtic Trading (Cornwall) Limited | Wholesale & retail | 2013 |
| CEM Deniz Catering Ltd | Hospitality | 2020 |
| Cemre 68 Ltd | Hospitality | 2025 |
| Cena Limited | Information & communication | 2010 |
| Centanex Limited | Manufacturing | 2009 |
| Central Projects Ltd | Hospitality | 2011 |
| Central Specsavers Limited | Wholesale & retail | 1991 |
| Central Visionplus Limited | Wholesale & retail | 1997 |
| Centre for Music Research and Education Ltd | Professional & scientific | 2020 |
| Centre Security Limited | Professional & scientific | 1987 |
| Centreline Coatings Ltd | Construction | 2022 |
| Centreline Marine & Joinery Ltd | Manufacturing | 2008 |
| Centreline Marine Holdings Ltd | Financial services | 2025 |
| Centrum Consulting Ltd | Professional & scientific | 2023 |
| Certus Financial Planning Limited | Financial services | 2009 |
| Cerys Kille Management Ltd | Professional & scientific | 2024 |
| Cetus Energy (UK) Ltd | Energy | 2012 |
| Cetus Hydro Energy Ltd | Energy | 2012 |
| Cetus Linear Propulsion Ltd | Transport & logistics | 2012 |
| Cetus Marine Ltd | Energy | 2012 |
| Cetus Tidal Energy Ltd | Energy | 2012 |
| Cetus Wave Energy Ltd | Energy | 2012 |
| Cetus Wind Energy Ltd | Energy | 2012 |
| CF Reed Limited | Real estate | 2017 |
| CG Hire Limited | Administrative & support | 2016 |
| Cg.Markets Ltd | Financial services | 2026 |
| CGC Management Consultancy Limited | Professional & scientific | 2025 |
| Cgmc 2014 Ltd | Households | 2014 |
| CH Business Solutions Ltd | Administrative & support | 2006 |
| Chafford Hundred Specsavers Limited | Wholesale & retail | 2018 |
| Chalk Construct Limited | Construction | 2022 |
| Chalk Creatives Ltd | Construction | 2015 |
| Challenge Sailcloth Limited | Wholesale & retail | 1991 |
| Chamber International Trading Limited | Other services | 2004 |
| Chamberlains Consultancy Ltd | Information & communication | 2020 |
| Chambers Energy Limited | Real estate | 2024 |
| Chambers Property Renovations Ltd. | Real estate | 2025 |
| Chambers Santoreau Limited | Construction | 2019 |
| Chambers Southern Counties Limited | Professional & scientific | 2011 |
| Chambers Southern Ltd. | Construction | 2009 |
| Chambers Southern Meadows Farm Limited | Agriculture & fishing | 2013 |
| Chambers Southern Properties Limited | Real estate | 2016 |
| Chandlers Ford Specsavers Limited | Wholesale & retail | 2018 |
| Change Levers Limited | Professional & scientific | 2023 |