| CSO Confidential Ltd | Information & communication | 2008 |
| Cspi Associates Limited | Professional & scientific | 2003 |
| Csquared Asset Management LLP | | 2008 |
| CSR Foods Limited | Hospitality | 2025 |
| Csta Consulting Limited | Administrative & support | 2022 |
| Csuk Ltd | Construction | 2024 |
| CSW Cladding Limited | Construction | 2018 |
| CT Investments (South) Ltd | Real estate | 2020 |
| Ctbr Limited | Health & social care | 2012 |
| Ctmvptrading Ltd | Wholesale & retail | 2026 |
| Ctoomer Ltd | Information & communication | 2022 |
| CTW Property Holding Ltd | Real estate | 2021 |
| Cubic Brands Limited | Wholesale & retail | 2002 |
| Cubic Digital Ltd | Manufacturing | 2012 |
| Cubular Limited | Information & communication | 2015 |
| CUE T Snooker Club Ltd | Hospitality | 2022 |
| Culatie Limited | Health & social care | 2021 |
| Culinae Limited | Hospitality | 2019 |
| Cullinan Property Investment Ltd | Real estate | 2022 |
| Cultivated Management Ltd | Information & communication | 2018 |
| Cultural Media Enterprise | Information & communication | 2003 |
| Culver House Marketing Ltd | Professional & scientific | 2017 |
| Culverden Developments Ltd | Construction | 2013 |
| Culverden Down Management Limited | Households | 2021 |
| Cumberland (Bursledon) Management Company Limited | Households | 1982 |
| Cumberland One Limited | Professional & scientific | 2014 |
| Cumbrian Way Management Company Limited | Households | 2014 |
| Cumin Lounge Asia Limited | Hospitality | 2025 |
| Cummins Property Management Limited | Other services | 2012 |
| CUP & Kettle Ltd | Hospitality | 2025 |
| Curaconn Ltd | Professional & scientific | 2020 |
| Curax Care Ltd | Health & social care | 2024 |
| Cure and Herring Ltd | Hospitality | 2023 |
| Curio Card Care Services Ltd | Other services | 2025 |
| Curio Vita Ltd | Other services | 2018 |
| Curiosity Media Limited | Information & communication | 2021 |
| Curious Bunnies Childcare CIC | Health & social care | 2026 |
| Curious Monkey Adventures Group Ltd | Information & communication | 2023 |
| Curl Company Limited | Information & communication | 2024 |
| Curly Bites Ltd | Hospitality | 2025 |
| Curness Engineering Services Ltd | Professional & scientific | 2023 |
| Curphey Wealth Management Ltd | Financial services | 2020 |
| Curran Dental Engineers Limited | Manufacturing | 2005 |
| Currie and Partners Ltd | Construction | 2024 |
| Curry & Co UK Limited | Hospitality | 2024 |
| Curry Clicks Limited | Professional & scientific | 2024 |
| Curry on Wheels Limited | Manufacturing | 2004 |
| Curry Taste Soton Ltd | Hospitality | 2025 |
| Curtiss & Sons Limited | Professional & scientific | 1960 |
| Curve Therapeutics Limited | Professional & scientific | 2019 |
| Cushy Ltd | Information & communication | 2022 |
| Custom Covers (1984) Limited | Manufacturing | 1983 |
| Custom Furniture & Interiors Ltd | Manufacturing | 2024 |
| Custom Keyboards (Print) Limited | Manufacturing | 1994 |
| Custom Landscapes Ltd | Administrative & support | 2026 |
| Custom Metalworx Limited | Manufacturing | 2011 |
| Custom Printing and Packaging Limited | Administrative & support | 2024 |
| Custom Sprays (Southern) Ltd | Wholesale & retail | 2023 |
| Customised Composites Ltd | Manufacturing | 2009 |
| CUT Online Limited | Administrative & support | 2022 |
| Cutesykink Limited | Wholesale & retail | 2013 |
| Cutler Developments Limited | Real estate | 2020 |
| Cutler Home Solutions Ltd | Construction | 2017 |
| Cutlers Guttering and Roofing Services Limited | Construction | 2022 |
| Cutter Hotel GB Ltd | Hospitality | 2025 |
| Cutting Edge Inc. Limited | Administrative & support | 2018 |
| Cutting Edge Projects Southern Ltd | Construction | 2013 |
| Cutting Edge Property Solutions Ltd | Construction | 2024 |
| CV ALL Travel Limited | Transport & logistics | 2025 |
| CVK Solutions Limited | Professional & scientific | 2017 |
| Cvts Services Ltd | Administrative & support | 2020 |
| Cvts Training Ltd | Administrative & support | 2020 |
| CW Advice Ltd | Financial services | 2020 |
| CW Holdings Ltd | Financial services | 2020 |
| CW24 Ltd | Administrative & support | 2024 |
| CWE Consulting Limited | Administrative & support | 2013 |
| CWM Management Limited | Professional & scientific | 2011 |
| CWP Electrical Ltd | Construction | 2021 |
| CWS Accounting Solutions Ltd | Professional & scientific | 2024 |
| CWSO15 Limited | Hospitality | 2023 |
| CX Shirley CIC | Education | 2024 |
| CX Southampton Ltd | Information & communication | 2024 |
| CXJ Limited | Financial services | 2015 |
| Cyber Search Partners Ltd | Administrative & support | 2020 |
| Cyber Tech Facilitation Services Ltd | Administrative & support | 2013 |
| Cyberbear Defence Ltd | Information & communication | 2025 |
| Cyberdrift Ltd | Information & communication | 2018 |
| Cybersecurity and Compliance Ltd | Wholesale & retail | 2025 |
| Cyclo Cross Racer Limited | Wholesale & retail | 2019 |
| Cyclone International Ltd | Other services | 2024 |
| Cyclorama Wall Ltd | Construction | 2023 |
| Cygnet Bay Ltd | Real estate | 2019 |
| Cykpyk Ltd | Construction | 2018 |
| Cynaroides Ltd | Health & social care | 2019 |
| Cynation Limited | Information & communication | 2015 |
| Cyndicut Radio Ltd | Information & communication | 2025 |
| Cyntox Limited | Information & communication | 2026 |
| Cypher Strategy Limited | Information & communication | 2017 |
| Cyprus Supplies Limited | Wholesale & retail | 2003 |
| Cyra Group Ltd | Construction | 2021 |