| DHJ Homes Private Limited | Real estate | 2025 |
| DHS Building Ltd | Manufacturing | 2018 |
| DHT Cars Ltd | Wholesale & retail | 2024 |
| DHV & SON Limited | Construction | 2013 |
| Diadem Services Limited | Health & social care | 2015 |
| Dial'N'Shine Ltd | Construction | 2025 |
| Diamond Care and Support Ltd | Health & social care | 2024 |
| Diamond Developments & Consultancy Ltd | Real estate | 2017 |
| Diamond Event Services Limited | Hospitality | 2024 |
| Diamond HC Rentals Limited | Transport & logistics | 2024 |
| Diamond Silver Service Limited | Transport & logistics | 2024 |
| Diamond Touch MNS Ltd | Other services | 2022 |
| Diamond Transport (Herts) Limited | Transport & logistics | 2010 |
| Diamond Vehicle Maintenance Limited | Wholesale & retail | 2024 |
| Diamond Wedding Cars Limited | Transport & logistics | 2024 |
| Diclass Equine Ltd | Extraterritorial | 2020 |
| Diclass Ltd | Wholesale & retail | 2020 |
| Dids Fincrime Consulting Ltd | Professional & scientific | 2023 |
| Different Cars Limited | Wholesale & retail | 2016 |
| DIG 2017 Enterprises Ltd | Wholesale & retail | 2024 |
| Digisecure Systems Ltd | Other services | 2018 |
| Digital APE Publishing Ltd | Information & communication | 2024 |
| Digital High Streets Limited | Information & communication | 2020 |
| Digital Infrastructure Accelerator Limited | Information & communication | 2020 |
| Digital Oblongs Ltd | Information & communication | 2016 |
| Digital Outcomes Limited | Professional & scientific | 2015 |
| Digitalpgm Ltd | Information & communication | 2024 |
| Digitize Pro Ltd | Professional & scientific | 2023 |
| Digswell Court Freehold Limited | Households | 2018 |
| Digswell Hill Management Company Limited | Households | 2001 |
| Digswell Lodge Management Company (NO.1) Limited | Real estate | 2008 |
| Digswell Lodge Management Company (NO.2) Limited | Real estate | 2008 |
| Diluted Clown Limited | Information & communication | 2024 |
| Dinaros Limited | Financial services | 2024 |
| Dinicom Removals Ltd | Transport & logistics | 2022 |
| Dinohosting (UK) Ltd | Information & communication | 2021 |
| Direct Accounting Limited | Professional & scientific | 2007 |
| Direct Cleaning US Ltd | Manufacturing | 2026 |
| Direct Drive Transport Solutions Limited | Transport & logistics | 2014 |
| Direct Excellence Limited | Education | 2025 |
| Disco Disco Ltd | Administrative & support | 2020 |
| Disco Factory UK Limited | Arts & recreation | 2019 |
| Discreet Hearing Ltd | Health & social care | 2013 |
| Disigns Limited | Professional & scientific | 2023 |
| Dispute Resolution Ombudsman | Other services | 2014 |
| Distant Voices Academy CIC | Other services | 2023 |
| Distillery VFX London Limited | Information & communication | 2024 |
| Ditsy Designs Ltd | Manufacturing | 2024 |
| Ditye Limited | Wholesale & retail | 2023 |
| Diverse Desire Ltd | Wholesale & retail | 2024 |
| Divya Kasturi Company CIC | Arts & recreation | 2024 |
| Dixons Dispatch Limited | Transport & logistics | 2003 |
| DJ Mike Readings Limited | Arts & recreation | 2019 |
| DJ Mike Readings Production Limited | Arts & recreation | 2023 |
| DJB Taillifts Ltd | Manufacturing | 2026 |
| DJC Carpentry Limited | Construction | 2023 |
| Djinnco Ltd | Wholesale & retail | 2026 |
| DJT Electrical Installations Ltd | Construction | 2024 |
| DK Technic Limited | Wholesale & retail | 2021 |
| DLE Scott Ltd | Information & communication | 2021 |
| DLG Media Ltd | Information & communication | 2010 |
| DLJ Home Improvement Ltd | Construction | 2018 |
| Dljc Holdings Limited | Professional & scientific | 2026 |
| Dlrc Group Holdings Limited | Administrative & support | 2026 |
| Dlrc Holdings Limited | Financial services | 2019 |
| Dlrc Ltd | Administrative & support | 2005 |
| DLT Management Ltd | Information & communication | 2016 |
| Dluxe Autos Ltd | Administrative & support | 2023 |
| DLV Solutions Limited | Information & communication | 2015 |
| DLW Productions Ltd | Other services | 2022 |
| DM the PM Ltd | Information & communication | 2024 |
| Dmode Music Limited | Information & communication | 2015 |
| DMT Flow Ltd | Construction | 2023 |
| Dna&Co Ltd | Transport & logistics | 2018 |
| DNV Consultancy Ltd | Professional & scientific | 2017 |
| Doggie Dash Playfield Ltd | Arts & recreation | 2025 |
| Dole Properties Limited | Real estate | 2001 |
| Dollysofdatchworth Limited | Hospitality | 2026 |
| DOM Martin Music Ltd | Arts & recreation | 2022 |
| DOM Thorpe Online Fitness Limited | Health & social care | 2017 |
| Domam Limited | Financial services | 2021 |
| Domantis Limited | Professional & scientific | 2000 |
| Dominic D Pharma Service Ltd | Real estate | 2018 |
| Domo Residential Limited | Real estate | 2017 |
| DON Churros Cafes Limited | Hospitality | 2026 |
| DON Churros Limited | Hospitality | 2023 |
| Donnelly Contract Carpets and Flooring Ltd | Wholesale & retail | 2013 |
| Donnington Street Limited | Real estate | 2021 |
| Donohoe Decorating Ltd | Construction | 2025 |
| Doodle DUB Sound Engineering Ltd | Information & communication | 2019 |
| Dorah Care Ltd | Health & social care | 2025 |
| DOT Electrical Smart Homes Ltd | Construction | 2020 |
| DOT Group International Limited | Manufacturing | 2001 |
| DOT Properties and Investments Limited | Real estate | 2024 |
| Double 6 Events Limited | Other services | 2017 |
| Douglas Green Studio Limited | Arts & recreation | 2021 |
| Downham Properties Limited | Real estate | 2018 |
| Downrow Limited | Real estate | 1963 |
| Downshift Transport Ltd | Transport & logistics | 2025 |
| Downtown Pizza and Kebab Ltd | Hospitality | 2022 |