| Defence LAB Self Protection Limited | Swadlincote | 2019 |
| Defence Leaders Limited | Haverhill | 2009 |
| Defence Safety Limited | Shaftesbury | 2023 |
| Defence Shield Systems Limited | Cambridge | 2025 |
| Defender Fire Systems Limited | Harrow | 2021 |
| Defender Training and Response Ltd | St. Asaph | 2025 |
| Degesh Healthcare Services Ltd | Manchester | 2025 |
| Deiconsilio Limited | Cardiff | 2022 |
| Dekontee Healthcare Services Limited | Corby, England, United Kingdom | 2020 |
| Delderfieldcare Ltd | Watford | 2025 |
| Delian Alliance Industries UK Ltd | St. Albans | 2024 |
| Delicare Ltd | London | 2012 |
| DELIVERED4YOU Limited | Knutsford | 2023 |
| Della Alarm Systems Ltd | Welling | 2025 |
| Delta Base Security(Dbs) Limited | London | 2019 |
| Delta Defence Limited | London | 2025 |
| Delta Defense Limited | London | 2025 |
| Deltonia Ltd | London | 2026 |
| Delwes Consultancy Limited | Sheffield | 2020 |
| Demand PR Ltd | London | 2021 |
| Demetercare Group Limited | Nottingham | 2021 |
| Demidebo Limited | Walsall | 2024 |
| Dennis Fire Service Ltd | Waltham Cross | 2024 |
| Denri-Care Limited | Mansfield | 2025 |
| Dental Arts Studio (Dental Care) Limited | Hounslow | 2009 |
| Deny Same Day Care Ltd | Walsall | 2022 |
| Deoyem Ltd | London | 2019 |
| Dependable Care for YOU Ltd. | Hinckley (Leicestershire) | 2023 |
| Dependable Healthcare Solutions Ltd | Cardiff | 2019 |
| Derbyshire Community Foundation | Belper | 1994 |
| Derbyshire Districts Citizens Advice Bureau | Buxton | 2002 |
| Desmond LN Ltd | Birmingham | 2025 |
| Destination Africa Group C.I.C. | Broad Lane | 2016 |
| Destiny Jubilee Care Limited | Mexborough | 2021 |
| Destiny Partnership Ltd | Aberdeen | 2019 |
| Destiny Pathways Care Ltd | Ilford | 2025 |
| Destna Services Ltd | South Ockendon | 2022 |
| Detectedx UK Limited | London | 2026 |
| Detek Fire & Security Services Limited | Leigh-On-Sea | 1995 |
| Detree Community Heart Hub Ltd | Barking | 2023 |
| Deux EX Machina Limited | London | 2026 |
| Developing Active Young Minds Ltd | Stratford-Upon-Avon | 2021 |
| Development Reimagined Ltd | London | 2018 |
| Devine Ultra Care Ltd | Camborne | 2023 |
| Devon School of Yoga Ltd | Taunton | 2012 |
| Devotion Integrated Care Ltd | Corby | 2018 |
| Deway Care Limited | Watford | 2019 |
| Dewise Limited | Newport | 2022 |
| Dexfire Limited | Stonehouse | 2022 |
| DFO Safestyle Limited | London | 2025 |
| DG Care & Support Services Ltd | Welwyn Garden City | 2025 |
| Dg&Ps Ltd | Camberley | 2024 |
| DGT Fire Safety & Compliance Ltd | London | 2025 |
| DH Fire Consultancy Limited | Southend-On-Sea | 2010 |
| DH Safety Consultants Limited | Warrington | 2026 |
| Dhcc Consultancy Limited | Harlow | 2021 |
| Dhruti Dabhi Ltd | Southampton | 2024 |
| DHS Care Ltd | Walsall | 2023 |
| Dhub Education Ltd | Manchester | 2021 |
| Diabetes Consults Ltd | Rochester | 2021 |
| Diabetes Wellness Hub Ltd | Horley | 2025 |
| Diai Care Limited | Maidstone | 2020 |
| Diamond Caregivers Limited | Gloucester | 2023 |
| Diamond Fire Extinguishers (Brindle & Sons) Limited | Cheslyn Hay | 1999 |
| Diamond Fire Stopping Limited | Chislehurst | 2024 |
| Diamond Health International Ltd | London | 2020 |
| Diamond Hearts Housing and Support Services Limited | Smethwick | 2025 |
| Diamond Joint Ventures Ltd | Belfast | 2025 |
| Diamond Lindsaygrace Ltd | Northampton | 2019 |
| Diamond Social Care Solution's Ltd | Corby | 2023 |
| Diamond Support Services Limited | London | 2019 |
| Diamondplus Care and Support Ltd | Oxford | 2025 |
| Diamonds Social Care Limited | Leeds | 2017 |
| Dianerose Limited | Waterlooville | 2024 |
| Dianeutleyhealth Ltd | Reading | 2025 |
| Diaspora Connect Ltd | Northampton | 2018 |
| Dichin Ltd | London | 2019 |
| Dichotic Dilemma Social Enterprise Ltd | Leicester | 2023 |
| DIE and Tool 1974 Co Ltd. | Wimborne | 2018 |
| Digbah Limited Company Limited | Sidcup | 2020 |
| Digisoiler Ltd | Abingdon | 2025 |
| Digitastic Ltd | Portsmouth | 2020 |
| Digitus Network Ltd | London | 2023 |
| Dignifi Support Ltd | Manchester | 2019 |
| Dignity Health Care Services Ltd | Leicester | 2021 |
| Dignity Healthcare Training Ltd | Glasgow | 2023 |
| Digzhc Ltd | Port Talbot | 2025 |
| Dijitools Limited | Westerham | 2020 |
| Dikachi Ltd | Tipton | 2018 |
| Diligence Healthcare Services Ltd | Birmingham | 2023 |
| Dilpet Ltd | London | 2023 |
| Dimambro R Contracting Ltd | Brough | 2020 |
| Diminuere Ltd | Harrogate | 2024 |
| Dimwalmo Ltd | Motherwell | 2022 |
| Dinwiddy Consulting Limited | Bognor Regis | 2023 |
| Diplomatic House Limited | London | 2024 |
| Diplomatic Security Services & Anti-Drugs ONG Ltd | Blackburn | 2023 |
| Direct Fire and Safety Limited | St Helens | 2007 |
| Direct Traffic Management Limited | Doncaster | 1992 |
| Direzione Ltd | Bristol | 2015 |