| Cyber-T Security Ltd | Stanmore | 2015 |
| Cyber-Train Limited | Bromley | 2025 |
| Cyberani Ltd | London | 2025 |
| Cyberfied Ltd | Dunstable | 2024 |
| Cyberfly Ltd | London | 2022 |
| Cyberkids AI Ltd | London | 2024 |
| Cybersafe Scotland Ltd | Aberdeen | 2022 |
| Cybersafeschools Ltd | London | 2023 |
| Cybersaur Arts Ltd | Folkestone | 2021 |
| Cybersmart Tutoring Limited | Pinner | 2025 |
| Cybersquad Kids Ltd | Epping | 2023 |
| Cyberstep Ltd | Leicester | 2024 |
| Cybertots (on the Green) Limited | London | 2003 |
| Cybertots at Acton Gardens Limited | London | 2020 |
| Cybertots at Copley Close Children`S Centre Ltd | London | 2009 |
| Cybertots at G.W.Q. Ltd | London | 2013 |
| Cybertots Limited | London | 1999 |
| Cyberwomen Groups C.I.C. | Mildenhall | 2023 |
| Cybolearn Limited | London | 2023 |
| Cybp Education Limited | London | 2024 |
| Cybsafe Holdings Limited | London | 2017 |
| Cybsafe Ltd | London | 2015 |
| Cycla Ltd | Wimborne | 2026 |
| Cycle Circle Limited | Ashford | 2019 |
| Cycle Coach School Ltd | London | 2023 |
| Cycle Community CIC | Ashford | 2016 |
| Cycle Confident Limited | Woking | 2009 |
| Cycle Leeds Limited | Leeds | 2014 |
| Cycle North CIC | Leeds | 2017 |
| Cycle Savvy Limited | Witney | 2023 |
| Cycle Systems Ltd | London | 2007 |
| Cycles Learning Centre Ltd | Chippenham | 2019 |
| Cycling Instructor Limited | Fulham | 2005 |
| Cycling Projects | Warrington | 1991 |
| CYCLING4YOU Ltd | Ilford | 2018 |
| Cyclist Next Door Limited | London | 2025 |
| Cyclist Training Ltd | Whitefield | 2008 |
| Cyclones Revolution Group Limited | Nottingham | 2025 |
| Cyclops Security Training Ltd | Ashford | 2026 |
| Cyd-Siarad CYF | Llandysul | 2023 |
| Cydag | Caerfyrddin | 2025 |
| Cydentity Academy Ltd | Porthcawl | 2025 |
| CYE & Co Consultants Ltd | South Croydon | 2025 |
| Cyebridge Online School Ltd | East Grinstead | 2020 |
| Cyfeillion Bach Cyfyngedig | Newport | 2012 |
| Cyfer Education Ltd | London | 2022 |
| Cygnet Day Nurseries Ltd | Bordon | 2002 |
| Cygnet Nursery (Kidlington) Limited | Beaconsfield | 2016 |
| Cygnets Art School Ltd | London | 2018 |
| Cygnets Childcare Nurseries Limited | Redhill | 2014 |
| Cygnets Day Nurseries (Bournemouth) Ltd | Bordon | 2005 |
| Cygnets Foundation CIC | London | 2025 |
| Cygnets Nursery Limited | London | 2005 |
| Cygnets Placements and Training Limited | Newcastle | 2023 |
| Cygnus Academies Trust | Swanscombe | 2016 |
| Cygnus Coaching & Development Limited | Carnforth | 2019 |
| Cygnus Education Limited | Devon | 1996 |
| Cygnus Enterprises Limited | Aberdeen | 2014 |
| Cygnus Teaching School Alliance Limited | High Wycombe | 2015 |
| Cyguides Ltd | London | 2025 |
| Cykel Yorkshire CIC | Bradford | 2023 |
| Cylch LDN Ltd | London | 2025 |
| Cylch Meithrin Seren Fach | Mountain Ash | 2015 |
| Cylch Meithrin Trefeurig | Aberystwyth | 2012 |
| CYM UNI Ltd | London | 2024 |
| Cymbrogi Community CIC | Kilgetty | 2021 |
| Cymbrogi Futures Ltd | Kilgetty | 2019 |
| Cymdeithas Genedlaethol Hywel DDA | Hendygwyn Ar Daf | 1984 |
| Cymerman Services Limited | Reading | 2023 |
| Cymoedd Creadigol CIC | Aberdare | 2020 |
| Cymru Care Training Limited | Llanelli | 1993 |
| Cymru Community Collaboration CIC | Llandysul | 2025 |
| Cymru Newydd Cyfyngedig | Tregaron | 2025 |
| Cymuned Cels Community CIC | Pentraeth | 2024 |
| Cymuned Gybolfa Limited | Blaenau Ffestiniog | 2022 |
| Cynefin Farm CIC | Newport | 2022 |
| Cynefin Outdoor Learning Ltd | Cardiff | 2025 |
| Cynefin Pamoja CIC | Newport | 2025 |
| Cynefin. Calon. Celf. Llantwit Major Festival of the Arts CIC | Cardiff | 2021 |
| Cynosure Holding Ltd | High Wycombe | 2023 |
| Cypf Development Services Limited | Liverpool | 2009 |
| Cypher Coding Limited | Fareham | 2016 |
| Cyrene Ltd | Ware | 2025 |
| Cyrille Regis Legacy Trust | Brierley Hill | 2018 |
| Cytacs UK Ltd | Wolverhampton | 2025 |
| Cytek Academy Ltd | Liverpool | 2026 |
| Cytrenia Dunkley Litchmore Education Ltd | London | 2021 |
| Czech & Slovak Club England C.I.C. | Warwick | 2013 |
| Czech & Slovak Club UK C.I.C. | Birmingham | 2013 |
| Czech & Slovak Community and School Bristol CIC | Bristol | 2019 |
| Czech and Slovak Community UK C.I.C. | Solihull | 2026 |
| Czech School Cambridge CIC | St. Neots | 2019 |
| Czech School Scotland CIC | Edinburgh | 2018 |
| Czech School Surrey CIC | Cobham | 2023 |
| Czech School Without Borders, London | London | 2010 |
| Cânsing Ltd | Mold | 2016 |
| Còmhla Learning CIC | Auchinloch | 2024 |
| Cúram Teoranta | Maghera | 2021 |
| D & D Childcare Services Limited | Leeds | 2011 |
| D & E Consulting Limited | Pinner | 2018 |