| Cherry Pick Talent Ltd. | Arts & recreation | 2016 |
| Cherry Tree Cottages (51) Management Company Limited | Households | 2024 |
| Cheshire Polythene Film Company Limited | Manufacturing | 1984 |
| Cheshire Taverns Limited | Wholesale & retail | 2005 |
| Chestnut Products,Limited | Construction | 1947 |
| Chestnut Tree Property Management Ltd | Real estate | 2011 |
| Chetwood (Beckton) Management Company Limited | Households | 1984 |
| Cheylesmore House Residents Association Company Limited | Households | 1988 |
| CHI Synergy Ltd | Construction | 2020 |
| Chic Superior Interiors Limited | Professional & scientific | 2021 |
| Chichester Walk Properties Limited | Real estate | 1989 |
| Chik Limited | Real estate | 2026 |
| Child Prodigy Academy Limited | Education | 2022 |
| Childerditch Hall Farm Nominees Limited | Real estate | 2010 |
| Children in Mind Limited | Health & social care | 2021 |
| Chim-Taylor Limited | Real estate | 2020 |
| Chine Brickwork & Development Ltd | Construction | 2002 |
| Chinnocks Wharf Management Company Limited | Households | 1994 |
| Chippconstruction Ltd | Construction | 2019 |
| Chipping Properties Limited | Real estate | 2024 |
| Chopra Commercial Ltd | Real estate | 2014 |
| Chris Inch Ltd | Public administration | 2023 |
| Chris Jacques Lighting Ltd | Construction | 2024 |
| Chrischem (UK) Ltd | Wholesale & retail | 2002 |
| Chrisp Family Holdings Ltd | Real estate | 2019 |
| Chrisp Family Partnership LLP | | 2019 |
| Christchurch Softplay and Laser Ltd | Administrative & support | 2016 |
| Chronic Consulting Ltd | Professional & scientific | 2009 |
| Chrysalis SEB Ltd | Administrative & support | 2014 |
| Church Hill Blinds Ltd | Wholesale & retail | 2007 |
| Church Mews Management Co. (Basildon) Limited | Households | 1985 |
| Church of GOD Mission International (Dagenham) UK Limited | Other services | 2011 |
| Churchward Car Sales Ltd | Wholesale & retail | 2017 |
| Churchwood Fisheries Ltd | Agriculture & fishing | 2014 |
| Churley's Building Surveyors Limited | Professional & scientific | 2012 |
| Cinders Wish Ltd | Wholesale & retail | 2015 |
| Circle of Light Ltd | Health & social care | 2018 |
| Cirrus Cloud Partners Ltd | Information & communication | 2025 |
| City & Town Security Ltd. | Administrative & support | 2013 |
| City Environmental Limited | Construction | 2002 |
| City on the Hill Kingdom Restoration Ministry Ltd | Other services | 2024 |
| City Pavilion (London) Limited | Households | 1998 |
| City Plant and Screeding (Globe Works) Ltd | Financial services | 2019 |
| City Plant and Screeding Limited | Construction | 2019 |
| City Social Limited | Professional & scientific | 2019 |
| City Zone.Uk Limited | Wholesale & retail | 2019 |
| City-Group UK Ltd | Professional & scientific | 2012 |
| Citywide Plant Ltd | Administrative & support | 2009 |
| CJ Demo Ltd | Construction | 2025 |
| CJ Dental Studio Ltd | Health & social care | 2020 |
| Cjas (Essex) Ltd | Professional & scientific | 2018 |
| CJH Freehold Ltd | Households | 2024 |
| CJS Engineering Services Limited | Construction | 2018 |
| CKK Service Maintenance Ltd | Manufacturing | 2019 |
| Claggan Limited | Financial services | 2021 |
| Claire Gevaux Creative Consulting Ltd | Arts & recreation | 2021 |
| Claire Honey Ltd | Professional & scientific | 2020 |
| Claire Nails and Beauty 63 Limited | Other services | 2026 |
| Clapgate Autos Ltd | Wholesale & retail | 2017 |
| Clapham Park (Metropolitan Countryside) LLP | | 2022 |
| Clapro Holdings Limited | Financial services | 2010 |
| Clapton Car Wash Ltd | Other services | 2025 |
| Clare O'Neill Solicitors Ltd | Professional & scientific | 2020 |
| Clarendon House (Chelmsford) Limited | Real estate | 2011 |
| Clarendon Road Limited | Wholesale & retail | 2008 |
| Clarendon Surveyors Limited | Professional & scientific | 2022 |
| Clarewood Group Ltd | Financial services | 2021 |
| Clarity Health & Care Ltd | Health & social care | 2025 |
| Clarke Infinity Limited | Wholesale & retail | 2003 |
| Clarkfield Properties Essex Limited | Real estate | 2026 |
| Clarkson Catering Limited | Hospitality | 2006 |
| Claryntic Ltd | Information & communication | 2026 |
| Classact Limited | Construction | 1996 |
| Classhire Limited | Administrative & support | 2026 |
| Classic Sinatra (UK) Ltd | Administrative & support | 2006 |
| Classygrass Ltd | Construction | 2013 |
| Clatts Investments Ltd | Financial services | 2025 |
| Clay Ratnage Daffin & Co Limited | Professional & scientific | 2002 |
| Clayton Finance Limited | Wholesale & retail | 1978 |
| CLC Car Sales (North West) Limited | Wholesale & retail | 2018 |
| CLC Car Sales (South East) Limited | Wholesale & retail | 2013 |
| CLC Consulting Services Limited | Professional & scientific | 2015 |
| CLC Utility Services Limited | Professional & scientific | 1994 |
| Clean CUT Interior Build Ltd | Construction | 2021 |
| Clean Slate SEO Ltd | Professional & scientific | 2024 |
| Clean Sparkle Ltd | Administrative & support | 2019 |
| Clear Excellence Ltd | Wholesale & retail | 2007 |
| Clear Fine Technologies Ltd | Information & communication | 2025 |
| Clear Solutions Facilities Management Limited | Real estate | 2022 |
| Clear View Finance and Protection Ltd | Financial services | 2021 |
| Clear Vision Medicare Limited | Health & social care | 2011 |
| Clearbrook Group PLC | Construction | 1975 |
| Clearbrook Holdings Limited | Financial services | 2000 |
| Clearpath Health Ltd | Health & social care | 2025 |
| Clemco Consulting Ltd | Administrative & support | 2011 |
| Clevely Co Limited | Information & communication | 2026 |
| Clevena Ltd | Administrative & support | 2025 |
| Clever Angle Limited | Information & communication | 2013 |
| Cleverley Done Technology Ltd | Information & communication | 2026 |
| Click PAY Solutions Management Ltd | Professional & scientific | 2024 |