| Canine Cabin Ltd. | Other services | 2016 |
| Capricorn Developments Limited | Construction | 1993 |
| Care and Passion Limited | Health & social care | 2018 |
| Care Talent Hire Ltd | Health & social care | 2026 |
| CARE81 Limited | Health & social care | 2014 |
| Carlota Care Ltd | Health & social care | 2019 |
| Carly-Ann Coaching Ltd | Health & social care | 2019 |
| Carole Yallop Consultancy Services Limited | Administrative & support | 2012 |
| Caroline Cavanagh Ltd | Health & social care | 2003 |
| Carringtoncrisp Limited | Professional & scientific | 2004 |
| Carrytek Ltd | Information & communication | 2022 |
| Cartwright Benefit Consultants Ltd | Financial services | 2012 |
| Cartwright Financial Solutions Ltd | Financial services | 2012 |
| Cartwright Group Limited | Financial services | 2008 |
| Carvex Ltd | Wholesale & retail | 2024 |
| Carvico Ltd | Real estate | 2025 |
| Cash Converters (Bognor) Ltd | Wholesale & retail | 2010 |
| Cashsentinel UK Limited | Other services | 2016 |
| Cass Consultancy Limited | Professional & scientific | 2023 |
| Castle & Pryor Limited | Construction | 1991 |
| Castles Builders & Decorators Limited | Construction | 2003 |
| Catalano Ltd | Professional & scientific | 2025 |
| Catalyst Cameras Limited | Administrative & support | 2011 |
| Catering Installation & Service Ltd | Manufacturing | 2023 |
| Cathyhouse Luxury Apartments Ltd | Professional & scientific | 2013 |
| Catrin Guynan Ltd | Professional & scientific | 2004 |
| Catts Enterprises Limited | Professional & scientific | 2013 |
| Catts Homes Limited | Real estate | 2017 |
| CB General Builders Ltd | Construction | 2025 |
| CB PR Ltd | Professional & scientific | 2023 |
| Cbamable Ltd | Information & communication | 2026 |
| CBN London Ltd | Financial services | 2020 |
| CBS Insight LLP | | 2024 |
| Ccie-Contracts Limited | Information & communication | 2008 |
| CCS Landscapes Ltd | Administrative & support | 2022 |
| Cdvet Natural Ltd | Wholesale & retail | 2024 |
| Cedar Trading International Limited | Wholesale & retail | 2003 |
| Cedarwood Consultancy Limited | Construction | 2010 |
| Cedarwood Property Developments Limited | Construction | 2014 |
| Cegeka UK Limited | Information & communication | 1976 |
| Celtic Burners Ltd | Arts & recreation | 2025 |
| Ceme Creative Ltd | Information & communication | 2025 |
| Centre of Gravity Group Ltd | Health & social care | 2020 |
| Century Golf Ltd | Arts & recreation | 2025 |
| Chalfont Advisory Ltd | Professional & scientific | 2025 |
| Challenge Centre Limited | Arts & recreation | 2012 |
| Chameleon Services (S.E) Ltd | Administrative & support | 2011 |
| Changing Perspectives by Kate Fletcher Ltd | Professional & scientific | 2026 |
| Channel Solutions and Services Ltd | Financial services | 2019 |
| Chaps Barbers Ltd | Other services | 2022 |
| Chat Play Read C.I.C. | Wholesale & retail | 2017 |
| Chautari Real Estate Ltd | Real estate | 2025 |
| Chcraft Limited | Wholesale & retail | 2018 |
| Chen Associates Limited | Education | 2001 |
| Cherubs Kindergartens Limited | Education | 2001 |
| Chicken Katai Ltd | Hospitality | 2025 |
| Chief Engineering Limited | Construction | 2020 |
| Child Connect Limited | Health & social care | 2021 |
| Childlife | Administrative & support | 1999 |
| Chill Pro Ltd | Construction | 2015 |
| Chipset Ltd | Manufacturing | 2014 |
| Chittolla Properties Limited | Real estate | 2023 |
| Chloe Waters Ltd | Professional & scientific | 2025 |
| Chobham Travel Studio Ltd | Administrative & support | 2015 |
| Chopra Brother & Sons Limited | Wholesale & retail | 2021 |
| Chris the Builder Limited | Real estate | 2012 |
| Chriscourt Residents Association Limited | Hospitality | 1995 |
| Christ Apostolic Church Surpassing Grace Assemblies Ltd | Other services | 2017 |
| Christabel Balfour Ltd | Manufacturing | 2022 |
| Christel M G Chaudet Limited | Information & communication | 2025 |
| Christie Kwezi Ltd | Health & social care | 2020 |
| Christigales Ltd | Health & social care | 2019 |
| Christmas Treeasy Ltd | Wholesale & retail | 2007 |
| Chrome & Nickel Ltd | Information & communication | 2008 |
| CHS Holdings Group Limited | Other services | 2023 |
| Church View (Oxford) Management Company Ltd | Households | 2013 |
| Cilix Limited | Information & communication | 2004 |
| Circuit Designs Ltd | Professional & scientific | 2012 |
| Circular Building Solutions Limited | Construction | 2024 |
| Cirrus Plus Limited | Professional & scientific | 2005 |
| City Key Tours Limited | Administrative & support | 2018 |
| City's Bazaar PVT Ltd | Wholesale & retail | 2025 |
| Civiltech Ltd | Construction | 2021 |
| Civiltech Property Ltd | Real estate | 2024 |
| CJ Honestcars Limited | Wholesale & retail | 2024 |
| CKR Property Investments Ltd | Real estate | 2024 |
| Cladtech Associates Limited | Professional & scientific | 2017 |
| Cladtech Holdings Limited | Financial services | 2026 |
| Cladtech Surveys Limited | Professional & scientific | 2026 |
| Claire Day Consulting Ltd | Professional & scientific | 2022 |
| Clanchy Consulting Limited | Information & communication | 2006 |
| Claremont Corporate Events Consultancy Ltd | Professional & scientific | 2025 |
| Clarity Media Limited | Information & communication | 2005 |
| Clark & Brandish Flooring Ltd | Construction | 2022 |
| Clark Studios Limited | Information & communication | 2012 |
| Class on Glass Ltd | Administrative & support | 2023 |
| Classic Race Simulators Limited | Administrative & support | 2013 |
| Classtasker UK Ltd | Education | 2025 |
| Clayton Aniline Company Limited | Manufacturing | 1897 |
| Clean Meal Co Ltd | Hospitality | 2021 |