| Duke of Kent School | Cranleigh | 1997 |
| Duke of UKE Tuition Limited | Eastbourne | 2013 |
| Duke Plant Training Ltd | Liverpool | 2024 |
| Duke Primary Scholars Limited | London | 2024 |
| Duke Traditional Music, Ltd | Coalville | 2023 |
| Duke UK Trust Limited | London | 2007 |
| Dukes Barn Company | Matlock | 2000 |
| Dukes Creative Learning Limited | Dunbar | 2025 |
| Dukes Education Ltd | London | 1999 |
| Dulwich College | London | 2012 |
| Dulwich College Enterprises Limited | London | 1995 |
| Dulwich College Enterprises Overseas Limited | London | 2007 |
| Dulwich Education Academy Ltd | London | 2025 |
| Dulwich Maths Limited | London | 2004 |
| Dulwich Music Academy Ltd | London | 2020 |
| Dulwich Prep & Senior | London | 2017 |
| Dulwich Table Tennis Club CIC | London | 2025 |
| Dulwich Tutors Ltd | London | 2009 |
| Dulwich Village Kids Club Ltd | East-Dulwich | 2013 |
| Dulydo Ltd | Kettering | 2022 |
| Dumb OX Learning International Ltd | Camberley | 2025 |
| Dumela Limited | London | 2025 |
| Dumera Limited | Preston | 2023 |
| Dumfries & Galloway Multicultural Association | Dumfries | 2011 |
| Dumfries and Galloway Outdoor and Woodland Learning Group (Dgowl) CIC | Newton Stewart | 2023 |
| Dumfries Curling Limited | Castle Douglas | 2018 |
| Dumfries Historic Buildings Trust | Dumfries | 2011 |
| Dumfries Slow Fashion Movement CIC | Dumfries | 2021 |
| Dumont Training Limited | Bedfordshire | 2004 |
| Dumpton School | Dorset | 1968 |
| Dunain Holdings Limited | Drumnadrochit | 2021 |
| Dunamic Limited | Milton Keynes | 2025 |
| Dunamis Capital Group Ltd | London | 2026 |
| Dunbar Childcare Limited | Dunbar | 2016 |
| Duncan Clifton Limited | Bristol | 2016 |
| Duncan Rhodes Painting Academy Limited | Nottingham | 2020 |
| Duncan’S Driving School Ltd | Glasgow | 2023 |
| Dundee Arts & Wellness Group Ltd. | Dundee | 2015 |
| Dundee First AID Training Ltd | Dundee | 2022 |
| Dundee Polish Saturday School CIC | Perth | 2015 |
| Dundee Science Centre Enterprises Limited | Dundee | 1998 |
| Dundee Tribe Cheerleaders CIC | Dundee | 2025 |
| Dundee Youth Music Theatre Ltd | Dundee | 2022 |
| Dundonald United Academy Ltd | London | 2023 |
| Dune Academy Ltd | Stoke-On-Trent | 2025 |
| Dunedin School | Edinburgh | 2000 |
| Dunelm Associates (T&D) Ltd | Sunderland | 2010 |
| Duneshots Regenfi Ltd | Clacton-On-Sea | 2026 |
| Dungaroos Pre-School Limited | Southampton | 2021 |
| Dungaroos Winchester Ltd | Southampton | 2024 |
| Dunhampton Wildlife & Educational Center Ltd | Dunhampton | 2014 |
| Dunkirks Training Limited | Nottinghamshire | 2019 |
| Dunlop Lions Football Club CIC | Leicester | 2026 |
| Dunloy Development Partnership | Ballymena | 2011 |
| Dunluce Family Centre Limited | Londonderry | 2002 |
| Dunn Kitchens Limited | Craigavon | 2021 |
| Dunn Psychology Ltd | Wolverhampton | 2019 |
| Dunnell Enterprises Ltd | Dunstable | 2025 |
| Dunnington Children | York | 2002 |
| Dunottar School Foundation Limited | Reigate | 1961 |
| Dunromin Visiting Therapy Dogs CIC | London | 2025 |
| Duns Scotus Trust | Northampton | 2013 |
| Dunstable Learning Centre Ltd | Dunstable | 2017 |
| Dunstable Training & Tuition Limited | Dunstable | 2017 |
| Dunster Global Education UK Limited | 14 Lyon Road Harrow | 2026 |
| Dunston Heath Stables Ltd | Staffordshire, Penkridge | 2019 |
| Dunstone Education Trust | Preston | 2009 |
| Dunteldar Limited | Sheerness | 2012 |
| Dunville College UK Ltd | London | 2023 |
| Dunya Driving Academy Ltd | Cambridge | 2025 |
| DUO (U.K.) Limited | Warminster | 1982 |
| DUO Beauty Clinic Limited | Mexborough | 2023 |
| DUO Education (International) Limited | Birmingham | 2026 |
| Duolearner Ltd | Wolverhampton | 2024 |
| Duolingo UK Limited | London | 2025 |
| Durcan Educational Limited | London | 2018 |
| Durdham Down Charitable Trust Limited | The Promenade Clifton Down | 2002 |
| Durera Ltd | Westcliff-On-Sea | 2015 |
| Durga School of Motoring Ltd | Hounslow | 2019 |
| Durham and Newcastle Diocesan Learning Trust | North Shields | 2017 |
| Durham Cathedral Schools Foundation | Durham | 1993 |
| Durham City Basketball Club CIC | Durham | 2026 |
| Durham Education Limited | London | 2024 |
| Durham Falconry Ltd | Durham | 2021 |
| Durham Kumon Ltd | Durham | 2025 |
| Durham Lifting Training Solutions Ltd | Middlesbrough | 2023 |
| Durham Music Hub CIC | Durham | 2026 |
| Durham Muslims Community | Newcastle Upon Tyne | 2022 |
| Durham Open Learning College Limited | Sunderland | 2011 |
| Durham School Langley Foundation | Durham | 2011 |
| Durham School of English Ltd | Durham City | 2018 |
| Durhams Transport Training Ltd | Stockton-On-Tees | 2014 |
| Durlston Court School Trust Limited | New Milton | 1973 |
| Durrington Multi Academy Trust | Worthing | 2014 |
| Durston House School Educational Trust Limited | London | 1985 |
| Durus at Home Ltd. | Bradford | 2025 |
| Dusemond Study Programmes Ltd | Skegness | 2015 |
| Dushinsky Trust Limited | London | 1992 |
| Dust Breeding CIC | Stroud | 2025 |
| Dustilie Day Nursery Ltd | Worcester | 2025 |