| Chris Harman Driving School Limited | Education | 2021 |
| Chris Warren and Partners Ltd | Professional & scientific | 2021 |
| Christmas Financial Planners Limited | Financial services | 2002 |
| Cirrus Laser Limited | Manufacturing | 1987 |
| City UK Trading Company Limited | Professional & scientific | 2017 |
| CJ Flooring Services Limited | Construction | 2025 |
| CL Brickwork Ltd | Construction | 2023 |
| Clair Court Management Limited | Real estate | 1980 |
| Claire Rainford Communications Limited | Professional & scientific | 2024 |
| Clairedesouza Limited | Wholesale & retail | 2018 |
| Clarke BMS Ltd | Construction | 2023 |
| CLC Sussex Limited | Manufacturing | 2018 |
| Cleaned With Joy Ltd | Administrative & support | 2023 |
| Clear Sky Energy Limited | Construction | 2019 |
| Clearly Vizable Ltd | Extraterritorial | 2013 |
| Clearpath Partnership Limited | Information & communication | 2020 |
| Clearwell Mobility Limited | Wholesale & retail | 2003 |
| Clevelands (Haywards Heath) Limited | Households | 2012 |
| Clientswoop Ltd | Information & communication | 2024 |
| Clinic 360 Limited | Financial services | 2015 |
| Clinkk Ltd | Information & communication | 2025 |
| Cloud Junction Ltd | Information & communication | 2025 |
| Cloud PI Consulting Ltd | Information & communication | 2019 |
| Clover Construction Limited | Construction | 2023 |
| Clym Property Ltd | Real estate | 2023 |
| CLZ Aviation Ltd | Wholesale & retail | 2025 |
| Cmgg Service Ltd | Professional & scientific | 2017 |
| CNG Operations Ltd | Wholesale & retail | 2025 |
| Coach With Chris Limited | Health & social care | 2024 |
| Coastal Stamp Auctions Limited | Other services | 2017 |
| Coco Spice Ltd | Extraterritorial | 2017 |
| Code:Hill Ltd | Information & communication | 2023 |
| Cole's Beer Garden Ltd | Hospitality | 2025 |
| College House N.Z. Trust | Education | 2012 |
| Colourful Limited | Health & social care | 2006 |
| Comparenet Limited | Information & communication | 2024 |
| Complihr Limited | Professional & scientific | 2026 |
| Compton Printing Limited | Manufacturing | 1992 |
| Concert for Change Ltd | Other services | 2020 |
| Concorde Media Limited | Professional & scientific | 2001 |
| Condrawlec Ltd | Professional & scientific | 2024 |
| Confident Carers Ltd | Extraterritorial | 2012 |
| Conservaroof UK Limited | Construction | 2025 |
| Cooper & SON Funeral Services Limited | Other services | 1995 |
| Cops Media Ltd | Information & communication | 2023 |
| Coriolis Projects Ltd | Construction | 2008 |
| Cornerstone IMC Ltd | Professional & scientific | 2016 |
| Cornwall Media Group Ltd | Information & communication | 2022 |
| Corporate Flight Deck Ltd | Transport & logistics | 2021 |
| Cottrell Engineering Services Ltd | Professional & scientific | 2026 |
| Countryside Construction (S East) Ltd | Construction | 2016 |
| County Piling Ltd | Construction | 2023 |
| Coversure Insurance Services (Brighton) Limited | Financial services | 2003 |
| Cowell Construction Ltd | Construction | 2021 |
| Cowley & Baker Ltd | Wholesale & retail | 2018 |
| Cowley UK Holdings Ltd | Financial services | 2018 |
| Cpkcreative Limited | Professional & scientific | 2024 |
| Craen Consulting Limited | Professional & scientific | 2008 |
| Creospace Limited | Construction | 2019 |
| Cromwell Financial Solutions Limited | Financial services | 2006 |
| CRS Southern Limited | Professional & scientific | 2013 |
| CRU Real Estate Holdings Ltd | Real estate | 2026 |
| Crystal Nails Bar Ltd | Other services | 2026 |
| CSS South Limited | Professional & scientific | 2019 |
| CSS South Properties Limited | Real estate | 2024 |
| CT Graylands LLP | | 2024 |
| Cuckfield Management Limited | Households | 2006 |
| Cult Media Ltd | Wholesale & retail | 2023 |
| Cura Muneris Limited | Health & social care | 2013 |
| Curly Pepper Trading Ltd | Hospitality | 2020 |
| Curry Dosah Limited | Hospitality | 2025 |
| Curry Flava Ltd | Hospitality | 2016 |
| Curry Mahal Online Ltd | Hospitality | 2025 |
| Cursitor Recruitment Limited | Administrative & support | 2025 |
| Customer Attuned Ltd | Professional & scientific | 2014 |
| Cutters Barn Limited | Other services | 2011 |
| CV Technic Limited | Administrative & support | 1999 |
| CW Electrical (Sussex) Limited | Construction | 2014 |
| Cybersurance Ltd | Information & communication | 2025 |
| Cytetech Limited | Manufacturing | 2016 |
| D G Mcewan Limited | Professional & scientific | 2015 |
| D J Carpentry Solutions Ltd | Manufacturing | 2015 |
| D P Mason Building & Renovations Ltd | Construction | 2016 |
| D.C. Electrical Solutions Southern Limited | Construction | 2015 |
| D.Durrant Brickworks Limited | Construction | 2018 |
| D.H.N. Limited | Professional & scientific | 2002 |
| DA Marketing Ltd | Information & communication | 2026 |
| Dairy Court Management Company (Burgess Hill) Limited | Professional & scientific | 2014 |
| Daith Medical Ltd | Health & social care | 2020 |
| DAJ Plumbing & Heating Ltd | Construction | 2020 |
| Dalewood Properties Limited | Real estate | 2025 |
| Dallas Coaching & Consulting Ltd | Information & communication | 2024 |
| Damas Consulting Limited | Professional & scientific | 2022 |
| Darren Waddell Limited | Administrative & support | 2023 |
| Dassa Media Ltd | Professional & scientific | 2023 |
| Datalect Limited | Information & communication | 2016 |
| Datura Systems Ltd | Information & communication | 2022 |
| Daughter of Thoth CIC | Administrative & support | 2024 |
| Dave Coulson Mobile Mechanic Limited | Wholesale & retail | 2015 |
| David Howes Steel Trading Limited | Wholesale & retail | 2018 |