| Chris Dexter Associates Limited | Administrative & support | 2016 |
| Chris Somner Dinghy Sales Limited | Arts & recreation | 2009 |
| CJR Medical Ltd | Health & social care | 2022 |
| Clark Williams Services Ltd | Information & communication | 2017 |
| Clear Angle Studios Ltd | Information & communication | 2013 |
| CLP Plastering Ltd | Information & communication | 2024 |
| CMD Scenic Services Ltd | Information & communication | 2014 |
| Colmans Services Ltd | Construction | 2022 |
| Colney AL2 Ltd | Hospitality | 2026 |
| Colsons Scenic Services Ltd | Information & communication | 2023 |
| Compasses Cars Ltd | Wholesale & retail | 2023 |
| Concannonc Ltd | Information & communication | 2024 |
| Consumables Superstore Limited | Wholesale & retail | 2008 |
| Corbiere 15 Ltd | Administrative & support | 2010 |
| Core Psychotherapy Ltd | Health & social care | 2022 |
| Cotelligence Limited | Information & communication | 2020 |
| Cowen Investments Limited | Construction | 2013 |
| Cowen Land Limited | Real estate | 2015 |
| Creativa FX Ltd | Manufacturing | 2021 |
| Creative Caves Ltd | Hospitality | 2023 |
| Cubixcraft Ltd | Information & communication | 2022 |
| Culnane Geomatics Limited | Administrative & support | 2013 |
| D Thompson Painting & Decorating Ltd | Construction | 2011 |
| D. T. Connor & Co. Ltd | Construction | 2021 |
| DAM Rigging Ltd | Information & communication | 2022 |
| Damon Havlin London Ltd | Construction | 2022 |
| Define-It Limited | Information & communication | 2023 |
| Delphi Food Products Limited | Hospitality | 1984 |
| Delphi Property Investments Ltd | Real estate | 2015 |
| DH Scenic Services Ltd | Administrative & support | 2011 |
| Direct Air Ltd | Energy | 2019 |
| Division by Zero Ltd | Information & communication | 2016 |
| DJB Scenic Ltd | Construction | 2024 |
| DJP Scenery Ltd | Information & communication | 2023 |
| DK Mccarthy Solutions Ltd | Construction | 2022 |
| DOB Maintenance Limited | Construction | 2015 |
| Doboy Film & TV Ltd | Information & communication | 2025 |
| Down to Earth (UK) Ltd | Administrative & support | 2011 |
| DR Cotrufo Ltd | Health & social care | 2016 |
| DR Mooz Ltd | Health & social care | 2023 |
| Dragonfly Performance Rigging Ltd | Information & communication | 2024 |
| Dunraven Street (London) Management Limited | Real estate | 2002 |
| E.C.S. Estates (Holdings) Limited | Real estate | 1956 |
| E.P.H Developments Ltd | Construction | 2015 |
| Eclipse Rigging & Film Services Ltd | Information & communication | 2022 |
| Edmonton Community Partnership | Education | 2015 |
| ELE Besooijen Designs Ltd | Professional & scientific | 2025 |
| Electravoyant Systems Ltd | Professional & scientific | 2024 |
| Elephant Rigging Ltd | Information & communication | 2024 |
| Eligarf Technologies (UK) Limited | Information & communication | 2012 |
| Elladoons Ltd | Other services | 2021 |
| Elmcroft Court(Hemel Hempstead)Residents' Association Limited | Households | 1971 |
| Embassy Machine Services Limited | Health & social care | 2001 |
| Emma Denby Ltd | Information & communication | 2022 |
| Emulsional Limited | Construction | 2021 |
| EP Global Group Ltd | Transport & logistics | 2000 |
| ESZ Software Ltd | Information & communication | 2022 |
| ETM Traffic Management Ltd | Transport & logistics | 2023 |
| Europe (HS) Limited | Construction | 2003 |
| Everway Limited | Real estate | 2023 |
| Everwright BTL Ltd | Real estate | 2026 |
| Everwright DEV Ltd | Construction | 2026 |
| Everwright Holdings Ltd | Financial services | 2025 |
| Exent Corporation Limited | | 1982 |
| Eyot Productions Limited | Arts & recreation | 2013 |
| F J Pistol Machine Services Limited | Wholesale & retail | 2001 |
| F.J. Pistol Holdings Limited | Administrative & support | 1997 |
| F.J. Pistol Machinery Limited | Manufacturing | 1961 |
| Fairway Property Investments Limited | Construction | 1986 |
| Fernscape Developments Ltd | Real estate | 2024 |
| Fidaro Developments Limited | Construction | 2025 |
| Film Graphic Solutions Ltd | Information & communication | 2026 |
| Filmspark Lighting Ltd | Information & communication | 2022 |
| Fine English Tailoring Limited | Wholesale & retail | 1999 |
| Firstings in Fibre Ltd | Information & communication | 2010 |
| Flame Tiling Ltd | Construction | 2009 |
| Fleetwood Commercials Ltd | Wholesale & retail | 2011 |
| Flore Data Ltd | Information & communication | 2025 |
| Flore Data Solutions Ltd | Information & communication | 2026 |
| Flying Brick Records Limited | Information & communication | 2021 |
| Frankenstein Ltd | Information & communication | 2025 |
| Freepart Limited | Construction | 1997 |
| Frogmore Garage Limited | Wholesale & retail | 2003 |
| Full Swing Events Ltd | Arts & recreation | 2024 |
| Funky Friends Ltd | Manufacturing | 2020 |
| G & D Plant Hire (Watford) Limited | Construction | 2015 |
| G B Scenic Plasterarts Ltd | Information & communication | 2016 |
| G R Bell Ltd | Information & communication | 2018 |
| GEM BUD 1 Chipette Ltd | Construction | 2022 |
| Geraldine Cooper Painting Ltd | Information & communication | 2023 |
| GHH Business Services Ltd | Administrative & support | 2022 |
| GHW Construction Ltd | Information & communication | 2021 |
| Glen Hydro Holdco Ltd | Financial services | 2018 |
| Global D&D Ltd | Hospitality | 2018 |
| Golf Day Gloss Limited | Administrative & support | 2014 |
| Gono Premier Properties Ltd | Real estate | 2025 |
| Grange Court Management (Herts) Limited | Households | 2019 |
| Gray FAB Limited | Professional & scientific | 2018 |
| Green FEN Ltd | Construction | 2025 |
| Gresham Homes Group Ltd | Real estate | 2024 |