| Cycling Events Limited | Preston | 2019 |
| Cycling Performance & Health Ltd | Cheltenham | 2023 |
| Cycling Shakespeare Limited | Wigan | 2020 |
| Cycling Sheffield Limited | Sheffield | 2018 |
| Cycling Time Trials | Stoke On Trent | 2002 |
| Cycling World CUP Ltd | Weybridge | 2020 |
| Cyclism Ltd | Witham | 2015 |
| Cyclo Art BUG Limited | Bath | 2023 |
| Cyclo BUG Limited | Bath | 2022 |
| Cyclo Trust | Matlock | 2011 |
| Cyclomania Ltd | Faringdon | 2018 |
| Cyclone Fitness Studio Ltd | Liverpool | 2023 |
| CYCLONE24 Limited | Cardiff | 2016 |
| Cyclones Revolution CIC | Nottingham | 2023 |
| Cyclopark | Gravesend | 2011 |
| Cyclops Art Ltd | Maidstone | 2012 |
| Cyclovision Limited | London | 2018 |
| Cyfeillion Cae'R Gors CYF | Bangor | 1997 |
| Cyfeillion Eglwys Llandegwning | Pwllheli | 2002 |
| Cyfeillion Ellis Wynne | Bae Colwyn | 1995 |
| Cyfeillion Swtan | Holyhead | 1998 |
| Cygnet Training Theatre & Cygnet Research Library | Exeter | 2000 |
| Cygnets and Swans Limited | Edinburgh | 2024 |
| Cygnets Model Boat Club Limited(The) | Gillingham | 1978 |
| Cygnus Live Ltd | Ellesmere Port | 2018 |
| CYI Services Limited | Bristol | 2023 |
| Cykl Haus Boutique Ltd | Hungerford | 2016 |
| Cylinder Limited | Woodbridge | 1997 |
| Cylindergallery Limited | London | 2024 |
| Cymdeithas Bethlehem Dyffryn Ceidrych Association Limited | Llandeilo | 2004 |
| Cymdeithas Cadwraeth Llanrhaeadr YC Preservation Society | Denbigh | 2012 |
| Cymdeithas Campau Celtaidd Cwmni Buddiant Cymunedol | Pen-Y-Bont Ar Ogwr | 2025 |
| Cymdeithas Chwaraeon Llandysul | Llandysul | 1988 |
| Cymdeithas Gychod Afon Nyfer AC Harbwr Trefdraeth | Newport | 2006 |
| Cymdeithas Maes Chwarae Rhydypennau CYF. | Aberystwyth | 2015 |
| Cymdeithas Pysgota Llandeilo Angling Association Cyfingedig | Llandeilo | 2011 |
| Cymric Archers Limited | Llanelli | 2025 |
| Cymru Football Foundation Limited | Newport | 1996 |
| Cynhyrchiadau IWX Productions Ltd | Cardiff | 2021 |
| Cynthia Liza Creative Ltd | London | 2021 |
| Cynthia Murphy Limited | Manchester | 2023 |
| Cynthiahoyievents Ltd | Bristol | 2022 |
| Cynyrchiadau Onnen Productions Ltd | Caerfyrddin | 2023 |
| Cyon Fitness Ltd | Wetherby | 2023 |
| Cypherdelic Limited | Cambridge | 2015 |
| Cyprian Musical Industries Limited | London | 2017 |
| Cyprus Wildlife Ltd | London | 2026 |
| Cypry Pool Fishery Limited | Bexley | 2013 |
| Cyril Unsworth Limited | Blackburn | 1945 |
| Cyrus Pattinson Boxing Academy CIC | Newcastle Upon Tyne | 2025 |
| Cyster Fitness Ltd | London | 2023 |
| Cyzman Enterprises Limited | Perth | 2024 |
| Czech the Music Events Ltd | Manchester | 2025 |
| Czepeku Ltd | Norwich | 2020 |
| Céad Music Ltd | Londonderry | 2019 |
| Cöre Hause Ltd | Nelson | 2025 |
| D & a Design Contracts Limited | Leicester | 1990 |
| D & a Designs Limited | London | 2022 |
| D & a Leisure Limited | Walsall | 2002 |
| D & a Music Limited | Oakham | 2007 |
| D & B Barratt Ltd | Ellesmere Port | 2021 |
| D & D Promotions Ltd | Preston | 2019 |
| D & G Events Limited | Cullompton | 2014 |
| D & G Fitness World Ltd | Blackpool | 2020 |
| D & H Associates (North East) Limited | Tyne & Wear | 2001 |
| D & H Events Group Ltd | Portsmouth | 2024 |
| D & H Packaging Limited | Cinderford | 2006 |
| D & K Golf Ltd | Penryn | 2020 |
| D & K Services UK Limited | Warrington | 2009 |
| D & L Entertainment Ltd. | Farnham | 2009 |
| D & L Productions Limited | London | 2009 |
| D & M Darts Limited | Weston-Super-Mare | 2021 |
| D & N Star Yachting Limited | Mexborough | 2010 |
| D & R Fitness Ltd | Kilwinning | 2025 |
| D & S Creations Events Ltd | Sheerness | 2022 |
| D & T Academy Limited | Bristol | 2017 |
| D & T Racing Ltd | Bristol | 2022 |
| D & W Leisure Ltd | Whitefield | 2021 |
| D a Events Ltd | Alfreton | 2024 |
| D a Tudhope Ltd | Durham | 2014 |
| D and a Fitness Ltd | Buntingford | 2025 |
| D and J Racing Ltd | Oldham | 2006 |
| D and R Motion Ltd | Blandford Forum | 2023 |
| D and S Costumes Ltd | Norwich | 2021 |
| D B E Global Limited | Bolton | 2012 |
| D B Events (GBR) Ltd | Ipswich | 2008 |
| D B R Engineering Limited | Cheshire | 2007 |
| D B Racing Ltd | Bromsgrove | 2015 |
| D Bradley Limited | Manchester | 2004 |
| D C Official Ltd | London | 2021 |
| D Chord Ltd | London | 2024 |
| D Cooper Underwater Services Limited | Bognor Regis | 2013 |
| D Crawford Group Limited | Motherwell | 2020 |
| D E Events Limited | North Lincolnshire | 2006 |
| D Events LDN Ltd | London | 2020 |
| D F Sound Limited | Edinburgh | 2015 |
| D Fitness UK Ltd | Telford | 2021 |
| D Freebairn Ltd | Altrincham | 2024 |
| D G Golf Pro Limited | Near Goole | 2006 |
| D G Sports Consultants Limited | Weybridge | 2009 |