| Church of England Educational Services Limited | London | 2017 |
| Church Square Nursery Limited | Sunbury-On-Thames | 2026 |
| Church Street Day Nursery Ltd | Telford | 2011 |
| Church Walk Pre-School Nursery Limited | Ulverston | 2005 |
| Churchdown School | Gloucester | 2011 |
| Churcher's College | Petersfield | 2017 |
| Churches Together in Earley and East Reading Schools Project | Reading | 2004 |
| Churches Visitor and Tourism Association | Chelmsford | 2002 |
| Churches' Training Company Ltd -the | Londonderry | 1993 |
| Churchill College Oxford Ltd | Beaconsfield | 2007 |
| Churchill House School of English Language Limited | Kent | 1971 |
| Churchill Language Services Limited | Wirral | 2005 |
| Churchtown Group Limited | Southport | 2026 |
| Churston Ferrers Grammar School | Brixham | 2010 |
| Churwell C.I.C. | Leeds | 2012 |
| Chynna Cole Educational Psychology Ltd | Frodsham | 2024 |
| CI Study Ltd | London | 2019 |
| Ciaea International Exchange Ltd | Birmingham | 2024 |
| Cianote Ltd | Feltham | 2025 |
| Ciao Ciao Family Ltd | London | 2026 |
| Ciao Ciao PRE School CIC | London | 2024 |
| Ciao!Lanarkshire CIC | Hamilton | 2025 |
| Ciaps Ltd | London | 2023 |
| Ciara Drums Ltd | Waltham Abbey | 2023 |
| Ciara Totten Ltd | Broughshane | 2022 |
| Ciausu Consulting Limited | London | 2025 |
| Cibtac Limited | Gloucester | 1977 |
| Cicek Tutoring Ltd | London | 2017 |
| Cicero Group UK Ltd | Birmingham | 2025 |
| Cicet Academy Limited | Chelmsford | 2024 |
| Cici Studios Ltd | London | 2025 |
| Cicm (Services) Limited | Peterborough | 1992 |
| CID - Children's Interactive Diary Ltd | London | 2025 |
| Cidari Education Limited | Blackburn | 2013 |
| CIE Global Awarding Body Limited | London | 2018 |
| CIE International Education Group Limited | North Yorkshire | 1995 |
| Cieh Limited | London | 1986 |
| Cienega Limited | Middlesex | 2006 |
| Cifa Education Ltd | London | 2022 |
| Cigdem Limited | Tottenham Hale | 2018 |
| Cigoldsmiths Ltd | London | 2023 |
| Ciha Ltd | Newport | 2025 |
| CIL Education Ltd | Cheltenham | 2012 |
| Cilm Hub Ltd | London | 2026 |
| Cima China Limited | London | 2005 |
| Cimt Maths Ltd | Exeter | 2025 |
| Cinbrava Ltd | London | 2025 |
| Cinch Development Ltd | Rayleigh | 2016 |
| Cinderford Artspace | Cinderford | 1991 |
| Cinderford Town Football Academy Limited | Gloucester | 2017 |
| Cinders Training Ltd | Upminster | 2023 |
| Cindrebay Education London Ltd | London | 2024 |
| Cindy Impey School Improvement Ltd | Norwich | 2022 |
| Cindy's Swim School Ltd | Esher | 2013 |
| Cinecertified CIC | London | 2024 |
| Cineindicator Limited | Woking | 2025 |
| Cinema for ALL Ltd | Sheffield | 2014 |
| Cinemaze Ltd. | London | 2024 |
| Cinenova Limited | London | 1983 |
| Cinetallent East Ltd | London | 2025 |
| Cinetallent Ltd | London | 2020 |
| Cinevisionary Ltd | Newhaven | 2024 |
| Cinn Learning & Development Ltd. | Southam | 2015 |
| Cinnamon Chalk Ltd | Reading | 2015 |
| Cinque Ports Sailing Club CIC | Ashford | 2025 |
| Cinque Ports Sailing Limited | Ashford | 2014 |
| Ciné Schools Ltd | Bolton | 2021 |
| Cioe&It Northern Ireland Ltd | Belfast | 2025 |
| CIP Associates Ltd | Whitchurch | 2025 |
| Cipd Forum Ltd | Ruislip, | 2025 |
| Cipd Modules Limited | Ruislip, | 2025 |
| Cipher Education Group Ltd | London | 2026 |
| Cipher Medical Consultancy Limited | Stockton-On-Tees | 2015 |
| Cipher Training Ltd | Chorley | 2025 |
| Circ-Hiit UK Ltd | Borehamwood | 2023 |
| Circadian Nest Nursery Limited | Bristol | 2025 |
| Circl Learning Ltd | Cirencester | 2018 |
| Circle & Centre CIC | London | 2025 |
| Circle 25 Welfare Association UK Ltd | Sunderland | 2025 |
| Circle Academy Ltd | Waltham Cross | 2021 |
| Circle Biodynamics Limited | Horsham | 2021 |
| Circle Collective CIC | Halesowen | 2025 |
| Circle Community Ltd | London | 2011 |
| Circle Doors Support CIC | London | 2026 |
| Circle Initiative Ltd | London | 2025 |
| Circle of Giving C.I.C. | Purley | 2025 |
| Circle of Justice Ltd | Atherstone | 2013 |
| Circle of Life CIC | Blackburn | 2025 |
| Circle of Life Events Ltd | Birmingham | 2022 |
| Circle of Life Rediscovery Community Interest Company | Lewes | 2007 |
| Circle of Life Training Ltd | Walsall | 2022 |
| Circle Square Star Limited | Cardiff | 2015 |
| Circle Virtual College Limited | London | 2014 |
| Circle+ CIC | London | 2025 |
| Circled Around Limited | Doncaster | 2019 |
| Circlegrouptech Ltd | Ruislip | 2021 |
| Circlejam CIC | Glasgow | 2025 |
| Circles ALT ED C.I.C. | Billericay | 2014 |
| Circles of Salam Ltd | Bradford | 2019 |
| Circles Project C.I.C. | Wolverhampton | 2025 |