| DCI MK Ltd | Construction | 2012 |
| Dcxworld.Com Ltd | Financial services | 1998 |
| DE LA Huliniere Holdings Ltd | Real estate | 2018 |
| Deans Farm | Administrative & support | 1991 |
| Declutter Dollies Ltd | Households | 2022 |
| Deepshots Limited | Wholesale & retail | 2011 |
| DEF Scenery Ltd | Manufacturing | 2024 |
| Delivered by Midwives Limited | Health & social care | 2018 |
| Dells Windows (Tring) Limited | Construction | 2012 |
| Dembe Theatre Services Ltd | Arts & recreation | 2024 |
| Densley Developments Ltd | Construction | 2019 |
| Dent Consulting Limited | Information & communication | 2008 |
| Denton P Consulting Ltd | Professional & scientific | 2026 |
| Design & Build Mavericks Ltd | Manufacturing | 2014 |
| Designer Labels Direct INT. Ltd | Wholesale & retail | 2018 |
| Deut 261 Ltd | Professional & scientific | 2016 |
| DEV Matters Limited | Information & communication | 2023 |
| Devito's Kitchens + Bathrooms Limited | Construction | 2018 |
| Devoin Ltd | Information & communication | 2018 |
| Dgsr Consultancy Limited | Professional & scientific | 2010 |
| DHR Contracts Limited | Financial services | 2021 |
| DHT Construction Ltd | Construction | 2024 |
| Digital Business Technology Services Group Ltd | Information & communication | 2023 |
| Digital Interfuse Limited | Information & communication | 2025 |
| Direct Lift Removal Ltd | Construction | 2006 |
| Djbmedia Ltd | Information & communication | 2019 |
| DJM Talent Limited | Administrative & support | 2018 |
| DLH Building Services Ltd | Construction | 2009 |
| DMF Management Co Limited | Households | 2023 |
| Dolan Accountancy Limited | Professional & scientific | 2017 |
| Dolan Contractor Group Limited | Professional & scientific | 2018 |
| Dolly Show Merch Ltd | Wholesale & retail | 2026 |
| Dolphin Swim Ltd | Education | 2023 |
| Doman Logistic Ltd | Transport & logistics | 2019 |
| Dotq Ltd | Information & communication | 2022 |
| Dougfield Limited | Real estate | 2023 |
| Dprn Engineering Solutions Ltd | Professional & scientific | 2024 |
| DR Eleanor Martin Clinical Psychology Ltd | Health & social care | 2026 |
| Drayton Foam Limited | Manufacturing | 2001 |
| DRB Consult Ltd | Professional & scientific | 2024 |
| Dreamteam Learning Limited | Administrative & support | 2011 |
| Drexel Ltd | Information & communication | 2024 |
| Druid Consultancy Limited | Information & communication | 2024 |
| Drylan Consulting Limited | Professional & scientific | 2014 |
| DS Multisports Ltd | Education | 2025 |
| Dtmw Services Ltd | Manufacturing | 2016 |
| Duero Advisory Ltd | Professional & scientific | 2024 |
| Duke Design Works Limited | Other services | 2012 |
| Duncan Gowers Consulting Ltd | Professional & scientific | 2025 |
| Dunstable Flooring Limited | Construction | 2020 |
| DVR Cloudcorp Ltd | Information & communication | 2019 |
| Dyslexia Solutions Hertfordshire Ltd | Education | 2011 |
| E,A,F Lining Ltd | Construction | 2020 |
| E-Learningplus (ELP) Limited | Education | 2019 |
| E.I.C. Insurance Services Ltd | Financial services | 1988 |
| E4 Service Management Ltd | Information & communication | 2014 |
| Earlco Consulting Limited | Professional & scientific | 2018 |
| EAS Technology Consulting Ltd | Information & communication | 2019 |
| Eastbury Engineering Consultancy Ltd | Professional & scientific | 2013 |
| EC3 Quantitive Ltd | Information & communication | 2019 |
| ECH Asset Solutions Ltd | Manufacturing | 2021 |
| Ecig Flavour.Com Limited | Manufacturing | 2014 |
| Ecig Formulations Limited | Manufacturing | 2015 |
| ED Consulting Services Ltd | Information & communication | 2023 |
| ED Hub Limited | Administrative & support | 2023 |
| ED Sales Limited | Administrative & support | 2023 |
| Eddington Solutions Limited | Information & communication | 2020 |
| Eden Design Installs Limited | Construction | 2022 |
| Edendene Limited | Professional & scientific | 2003 |
| Edendene Trustees Limited | Professional & scientific | 2024 |
| EFC Consulting Limited | Information & communication | 2019 |
| EFS Service & Maintenance Ltd | Administrative & support | 2024 |
| Eight Roman Limited | Professional & scientific | 2025 |
| Eite Consulting Limited | Professional & scientific | 2011 |
| Ela's Cakes Ltd | Wholesale & retail | 2024 |
| Electrical Fire and Security Ltd | Construction | 2021 |
| Elevate Automotive Ltd | Wholesale & retail | 2021 |
| Elevation Scaffolders Ltd | Construction | 2021 |
| Eligius Recruitment Limited | Administrative & support | 2011 |
| Elocventa Limited | Professional & scientific | 2015 |
| Ember & Flame Ltd | Wholesale & retail | 2024 |
| Emdel Ltd | Other services | 2019 |
| Emerald Hill Engineering Ltd | Professional & scientific | 2022 |
| Emergence Foundation | Education | 1993 |
| Emet Financial Planning Ltd | Financial services | 2023 |
| Emet Financial Services Limited | Financial services | 2015 |
| Emet Wealth Planners Ltd | Financial services | 2023 |
| Eminence Holdings Ltd | Administrative & support | 2025 |
| Empower AV Solutions Ltd | Professional & scientific | 2008 |
| Empower Sales Limited | Information & communication | 2022 |
| Emrys Alchemy Ltd | Extraterritorial | 2022 |
| Emsada Limited | Information & communication | 2020 |
| Enemite Ltd | Wholesale & retail | 2010 |
| Enerlyze Consulting Ltd | Professional & scientific | 2025 |
| Engineering in Medicine Limited | Professional & scientific | 1987 |
| Englefield Consulting Ltd | Professional & scientific | 2016 |
| English Alive Limited | Education | 2000 |
| Ennis & Brown Ltd | Wholesale & retail | 2016 |
| Epixion Consulting Ltd | Information & communication | 2025 |
| Eqwine Bar Ltd | Hospitality | 2024 |