| Cole Financial Associates Limited | Financial services | 2018 |
| Colebrooks Property Ltd | Real estate | 2026 |
| Coleridge Mews (Worthing) Limited | Real estate | 2000 |
| Coles and Carter Limited | Wholesale & retail | 2018 |
| Colibri (U.K.) Limited | Hospitality | 2018 |
| Colinwood Ltd | Information & communication | 2025 |
| Collaborate Works Consultancy Limited | Professional & scientific | 2024 |
| Collier Building Limited | Construction | 2015 |
| Colliers Property Investments Limited | Real estate | 2017 |
| Collingwood House Limited | Households | 1964 |
| Collins and Uncle Limited | Construction | 2022 |
| Colour by Fawn Ltd | Information & communication | 2025 |
| Colour Spray UK Ltd | Construction | 2019 |
| Coloured Courts Ltd | Construction | 2002 |
| Colours Foods Limited | Hospitality | 2023 |
| Colstock Developments Ltd | Construction | 2015 |
| Colstock Holdings Ltd | Financial services | 2015 |
| Colstock Limited | Wholesale & retail | 2009 |
| Columbia Management Ltd | Other services | 2025 |
| Colville Care Limited | Health & social care | 1997 |
| Colworth Farm LLP | | 2017 |
| Comber Associates Limited | Construction | 2007 |
| Comedyshortsgamer Limited | Arts & recreation | 2012 |
| Command Post Media Limited | Information & communication | 2011 |
| Comment IT Ltd | Information & communication | 2013 |
| Commerce Interact Limited | Professional & scientific | 2001 |
| Communication Engineering Limited | Professional & scientific | 2017 |
| Communication Supplies Limited | Wholesale & retail | 2017 |
| Communications Inc Limited | Professional & scientific | 2003 |
| Community Inspired Limited | Information & communication | 2002 |
| Compareyourtech Limited | Information & communication | 2024 |
| Compart Services Ltd | Manufacturing | 2021 |
| Compass Accountancy Ltd | Professional & scientific | 2019 |
| Compass Dance Studios Ltd | Arts & recreation | 2011 |
| Compass Partnership Limited | Professional & scientific | 1986 |
| Compass Travel (Sussex) Ltd | Transport & logistics | 2000 |
| Complete Design Engineering Consultancy Limited | Administrative & support | 2008 |
| Complete Lift Services Limited | Construction | 1998 |
| Complete Turf Care Ltd | Real estate | 2017 |
| Compliance Advisory Ltd | Professional & scientific | 2016 |
| Compliance Support Ltd | Professional & scientific | 2024 |
| Compnd Coaching Ltd | Arts & recreation | 2025 |
| Component Moulders Limited | Extraterritorial | 1968 |
| Comptonmay Limited | Real estate | 2022 |
| Concept Equipment Limited | Manufacturing | 1998 |
| Concierge Wealth Management Limited | Financial services | 2011 |
| Concilio Limited | Administrative & support | 2003 |
| Concorde Counselling Limited | Health & social care | 2019 |
| Concrete Flooring Solutions Ltd | Construction | 2010 |
| Condor Golf Services Ltd | Wholesale & retail | 2026 |
| Conference Zone Limited | Professional & scientific | 2021 |
| Conn Artists Theatre Company Limited | Arts & recreation | 2015 |
| Connaught Leisure Developments Ltd | Real estate | 2012 |
| Connaught Leisure Investments Ltd | Extraterritorial | 2012 |
| Connaught Leisure Limited | Arts & recreation | 1980 |
| Connect Health Limited | Information & communication | 2026 |
| Connect Media (Sussex) Ltd | Wholesale & retail | 2010 |
| Connecta Renewables Ltd | Administrative & support | 2026 |
| Connectedthecompany Ltd | Education | 2025 |
| Connie Healthcare Services Limited | Health & social care | 2016 |
| Connolly Neuro Limited | Health & social care | 2021 |
| Conpute Limited | Construction | 2014 |
| Conscious Learning Limited | Education | 2020 |
| Conserve Photography Ltd | Information & communication | 2016 |
| Consortium Business Solutions Ltd | Administrative & support | 2012 |
| Constantia Estates Limited | Construction | 2005 |
| Constantine Healthcare Ltd | Health & social care | 2024 |
| Construct Manage Maintain Limited | Construction | 2012 |
| Construction Dynamics Limited | Professional & scientific | 2005 |
| Construction Industry Software Limited | Information & communication | 2023 |
| Construction Industry Tax Solutions Ltd | Administrative & support | 2018 |
| Construction Management Contracts Limited | Professional & scientific | 2013 |
| Construction People Solutions Limited | Professional & scientific | 2021 |
| Construction People Specialists Ltd | Professional & scientific | 2024 |
| Construction Survey Group Limited | Professional & scientific | 2020 |
| Constructive Insights Limited | Professional & scientific | 2025 |
| Consultancy Clinic Limited | Health & social care | 2016 |
| Consultant Dietetic Services Ltd | Health & social care | 2012 |
| Consultero Limited | Professional & scientific | 2020 |
| Consulting Circles Limited | Health & social care | 2007 |
| Consumer Tech Limited | Professional & scientific | 2019 |
| Contemporary Coaching Limited | Health & social care | 2015 |
| Contexa Ltd | Professional & scientific | 2019 |
| Continuum Energy Consultants Ltd | Professional & scientific | 2026 |
| Contrast Clothing Ltd | Wholesale & retail | 2020 |
| Control Equipment Solutions Limited | Administrative & support | 2011 |
| Control Freq Limited | Manufacturing | 2007 |
| Control Measures Ltd | Professional & scientific | 2021 |
| Control-F Ltd | Information & communication | 2006 |
| Control-F Trustees Ltd | Other services | 2026 |
| Controlec Limited | Administrative & support | 2004 |
| Convenience Specialists UK Limited | Wholesale & retail | 2014 |
| Conway Edwards Property Company Ltd | Real estate | 2016 |
| Cook Elite Ltd | Manufacturing | 2020 |
| Cookson Factory Ltd | Information & communication | 2018 |
| Coole Bevis Property Investments Limited | Real estate | 2026 |
| Coole Bevis Wealth Management Limited | Financial services | 2009 |
| Coolground Properties Limited | Financial services | 2016 |
| Cooper Adams Estates Limited | Real estate | 2010 |
| Copaul Services Limited | Professional & scientific | 2015 |