| Daedalus Software Ltd | Information & communication | 2018 |
| Dame Alice Owen's School Music Centre Limited | Education | 1993 |
| Daracore Limited | Other services | 2018 |
| Daren Cook Design Limited | Administrative & support | 2008 |
| Daroy Gordon Ltd | Professional & scientific | 2002 |
| Dartland Properties Limited | Other services | 2004 |
| Data Engineering (Hoddesdon) Limited | Manufacturing | 2006 |
| Dataco IT Limited | Information & communication | 2008 |
| Datacore Software UK Ltd | Information & communication | 2000 |
| Dataplex Technology Limited | Information & communication | 2000 |
| Datascan (Europe) Ltd | Information & communication | 2018 |
| Dataweb Solutions Ltd | Extraterritorial | 1997 |
| Datawizard (UK) Limited | Information & communication | 1993 |
| Datum Resin Flooring Ltd | Construction | 2025 |
| Dave Bowe Limited | Arts & recreation | 2000 |
| David Carr Consulting Engineers Limited | Professional & scientific | 1995 |
| David Doyle Estate Agents (Hemel Hempstead) Limited | Real estate | 2000 |
| Davisa Holdings Ltd | Households | 2021 |
| Dawnchurch Properties Limited | Real estate | 1987 |
| Daycharm Limited | Real estate | 2004 |
| DAZ Idris Limited | Construction | 2017 |
| DCM Consulting Ltd | Construction | 2002 |
| DCT Systems Limited | Administrative & support | 2003 |
| DDN Car Sales Ltd | Wholesale & retail | 2019 |
| DE Bohun Care Ltd | Health & social care | 2000 |
| DE Havilland Moth Club Limited | Arts & recreation | 1996 |
| Dean Ivory Racing Limited | Arts & recreation | 2002 |
| Decisions Limited | Professional & scientific | 1999 |
| Decorating Division Limited | Construction | 2004 |
| DEL Gentleman Limited | Arts & recreation | 2003 |
| Delal Bistro Ltd | Hospitality | 2019 |
| DEN Invest Ltd | Financial services | 2025 |
| Dendron Brands Limited | Manufacturing | 2020 |
| Dendron Properties Limited | Construction | 2020 |
| Dens Limited | Health & social care | 2002 |
| DER Homes Limited | Real estate | 2021 |
| Derhan Ltd | Hospitality | 2023 |
| Designer Eyes Limited | Wholesale & retail | 2001 |
| Desklogic Limited | Professional & scientific | 1996 |
| Desktop System Consultants Limited | Information & communication | 1990 |
| Devaero Design Limited | Professional & scientific | 1997 |
| Dexson Properties Ltd | Real estate | 2022 |
| Dexter Management Limited | Real estate | 2002 |
| DH Retail Group Ltd | Wholesale & retail | 2024 |
| Diamond Enterprises (UK) Ltd | Manufacturing | 1994 |
| Diana Wilkinson Limited | Arts & recreation | 2002 |
| Dickson Estates Ltd | Real estate | 2018 |
| Digital Chaos Limited | Information & communication | 1995 |
| Digital Machine Ltd | Information & communication | 2016 |
| Digital Services Limited | Information & communication | 2002 |
| Digitaria Ltd | Information & communication | 1998 |
| Dileksoy Express Ltd | Wholesale & retail | 2020 |
| Dincer Properties Ltd | Real estate | 2021 |
| Diorama Jewels Limited | Wholesale & retail | 2025 |
| Direct Path Solutions Limited | Information & communication | 2004 |
| District and Modern Stores Limited | Wholesale & retail | 2003 |
| Diverse Corporation Limited | Health & social care | 1998 |
| DJB Carpentry & Building Limited | Construction | 2025 |
| DM Verulam Consulting Ltd | Construction | 2024 |
| DMD Motors Ltd | Wholesale & retail | 2024 |
| Dogldn Ltd | Wholesale & retail | 2019 |
| DOL Entertainment Limited | Hospitality | 2025 |
| Domesticare Products Limited | Wholesale & retail | 2003 |
| Domusea (Boxgrove) Limited | Construction | 2014 |
| DON Street Limited | Construction | 2000 |
| Done & Dusted Enterprises Limited | Administrative & support | 2007 |
| Downing Compliance Limited | Information & communication | 1996 |
| Downside Limited | Professional & scientific | 1995 |
| DR John Limited | Extraterritorial | 2002 |
| Dr.Nag-Cardiac Surgery Ltd | Health & social care | 2019 |
| Dreamcatcher London Limited | Health & social care | 2006 |
| Dried Fruit Mine Limited | Wholesale & retail | 2015 |
| Driving Motivation Limited | Other services | 2007 |
| DRS Marketing Limited | Information & communication | 2003 |
| DS Financial Consultancy Ltd | Professional & scientific | 2025 |
| Dual HEX Erciser Limited | Manufacturing | 2005 |
| Dunbar Cove LLP | | 2023 |
| Dunmow Plumbing & Heating Limited | Other services | 2007 |
| Dwyer Investments Limited | Wholesale & retail | 1972 |
| DX Caring Services Limited | Health & social care | 2014 |
| Dynamic Visuals | | 1991 |
| Dysfunction Media Limited | Information & communication | 2002 |
| Dyslexia Academic Support Tutors Limited | Education | 2001 |
| E-Ntire Ventures Ltd | Administrative & support | 2001 |
| E-Scribe Limited | Information & communication | 1996 |
| E. Corr Limited | Construction | 2002 |
| E.J. Duncan Ltd | Administrative & support | 1996 |
| E.J.Woollard Limited | Wholesale & retail | 1998 |
| E.P.G. Publishing Limited | | 1992 |
| E.P.Joseph Limited | Financial services | 1967 |
| E.S. Moss Limited | Construction | 2002 |
| Eades Consultancy Services Limited | Administrative & support | 2007 |
| Eagle Car Sales Limited | Wholesale & retail | 1993 |
| Eagle Grace Ltd | Wholesale & retail | 2002 |
| Earnest Healthcare Services Ltd | Health & social care | 2026 |
| East Finchley DRY Cleaners Ltd | Other services | 2022 |
| East Hill Kebab Ltd | Hospitality | 2024 |
| Eastcote Astro Limited | Arts & recreation | 1996 |
| Eastern Consumer Electronics Limited | Professional & scientific | 1992 |
| Eastside Nursery Ltd | Agriculture & fishing | 2003 |