| GSG Building & Renovations Limited | Construction | 2025 |
| GST Contracts Ltd | Construction | 2023 |
| GT Maintenance Services Ltd | Construction | 2016 |
| GT Peter ST Apartment Management Company Limited | Households | 2014 |
| GTB Agency Limited | Real estate | 2019 |
| Gtec (South) Limited | Other services | 2024 |
| Gtec Metal Fabrication Limited | Administrative & support | 2014 |
| Gtona Management Limited | Real estate | 2003 |
| Guaranteed Care Ltd | Health & social care | 2026 |
| Gugumuk UK Limited | Wholesale & retail | 2023 |
| Guildmark Capital Group Limited | Professional & scientific | 2013 |
| Guildmark Capital Holdings Limited | Professional & scientific | 2012 |
| Guildtrader Limited | Professional & scientific | 2006 |
| Gurrey Motors Limited | Wholesale & retail | 2010 |
| GWB Financial Services Ltd | Financial services | 2017 |
| GXL Camera Limited | Wholesale & retail | 2019 |
| Gypsies and Travellers Essex Community Interest Company | Education | 2025 |
| H & Co (ST Albans) Ltd | Other services | 2024 |
| H & Co Barbers Ltd | Other services | 2020 |
| H & G Brickwork Limited | Construction | 2023 |
| H a MAY Services Limited | Administrative & support | 2022 |
| H Consulting & Coaching Ltd | Professional & scientific | 2018 |
| H E B Associates Limited | Professional & scientific | 2022 |
| H Norris Legal Services Limited | Professional & scientific | 2014 |
| H R Inventory Limited | Wholesale & retail | 2023 |
| H S M Trading Limited | Other services | 2021 |
| H.C. Plant Limited | Wholesale & retail | 1977 |
| H.D.Collins Limited | Manufacturing | 1960 |
| H.W.Taylor Engineering(Hertford)Limited | Professional & scientific | 1961 |
| HA Youngblood Limited | Construction | 2014 |
| Habanada Consulting Ltd | Professional & scientific | 2021 |
| Habeo Talent Limited | Administrative & support | 2017 |
| HAD ME at Hello Limited | Hospitality | 2024 |
| Hadham Road Management Limited | Households | 2005 |
| Hadley House Management Company Ltd | Households | 2007 |
| Hadmas Ltd | Administrative & support | 2021 |
| Hagsdell Estate Ltd | Real estate | 2022 |
| Hailey Hall Academy Trust | Education | 2015 |
| Haileybury Academy Trust | Education | 2015 |
| Haileybury Enterprises Limited | Hospitality | 1993 |
| Hair by COX Ltd | Other services | 2022 |
| Hair Raizin Experience Limited | Other services | 2011 |
| Hair to Ware Ltd | Wholesale & retail | 2011 |
| Halford 71 Limited | Hospitality | 2023 |
| Hallcroft House (Soham) Residents Association Limited | Households | 1992 |
| Hallways Management Limited | Professional & scientific | 2024 |
| Hally Promotions Limited | Administrative & support | 2022 |
| Haminados Ltd | Hospitality | 2005 |
| Hammond Vets Limited | Professional & scientific | 2013 |
| Hamonde Park (Two) Edgware Management Company Limited | Households | 1994 |
| Hand on Heart Celebrant Ltd | Other services | 2021 |
| Hank Investments Limited | Real estate | 2018 |
| HAO Ming Electronic Commerce Co., Ltd | Extraterritorial | 2021 |
| HAPPY2BHOME Limited | Health & social care | 2026 |
| Haptc Limited | Other services | 2014 |
| Harbrine Limited | Wholesale & retail | 1993 |
| Hari SAI Ltd | Wholesale & retail | 2017 |
| Harington Glass Limited | Wholesale & retail | 1999 |
| Harleys Herts Ltd | Hospitality | 2025 |
| Harlow BBQ Ltd | Hospitality | 2018 |
| Harmony Spaces Limited | Real estate | 2021 |
| Harpenden Building Solutions Ltd | Construction | 2020 |
| Harpenden Properties Limited | Construction | 2008 |
| Harresca Ltd | Real estate | 2025 |
| Harrison Business Consultancy Ltd | Professional & scientific | 2023 |
| Harrison Hayes Ventilation Holdings Limited | Construction | 2024 |
| Harrison Hayes Ventilation Limited | Construction | 2015 |
| Harts Radiators Limited | Manufacturing | 2002 |
| Harvey Benson Limited | Professional & scientific | 2014 |
| Harvtech Ltd | Information & communication | 2021 |
| Hatch Illustration & Design Ltd | Information & communication | 2015 |
| Hatville Limited | Hospitality | 1992 |
| Hatwel Consultants Limited | Administrative & support | 2023 |
| Hawkes Civil Engineering Ltd | Construction | 2012 |
| Hayley Dolan Psychology Limited | Health & social care | 2021 |
| Haywindows Limited | Construction | 2020 |
| HBS Bloomfield Limited | Construction | 2021 |
| HBS Steel Ltd | Construction | 2025 |
| HC Environmental Ltd | Construction | 2021 |
| HD Property Ltd | Real estate | 2024 |
| HD Window Cleaning Ltd | Administrative & support | 2024 |
| Hd&Os Productions Ltd | Arts & recreation | 2026 |
| HDM Installations Limited | Manufacturing | 2009 |
| HDS Construction Limited | Construction | 2010 |
| Headspace Properties Belfast Limited | Administrative & support | 2018 |
| Health, Wellness & Dance Co. Ltd | Education | 2014 |
| Healthy Flavour Time Ltd | Hospitality | 2023 |
| Healthy Savvy Limited | Professional & scientific | 2024 |
| Heartbury Services Ltd | Transport & logistics | 2021 |
| Hearts Autos Ltd | Wholesale & retail | 2022 |
| Heath Rigging Ltd | Information & communication | 2015 |
| Heather London Limited | Construction | 2022 |
| Helab Limited | Other services | 2023 |
| Helderberg Ltd | Real estate | 2019 |
| Helix Design Solutions Limited | Construction | 2012 |
| Hemlock Recordings Ltd | Information & communication | 2010 |
| Henmarsh Consultancy Ltd | Other services | 2017 |
| Henry Ekins Limited | Real estate | 2009 |
| Henstan Estates Ltd | Real estate | 2018 |
| Herbotany Health Ltd | Agriculture & fishing | 2019 |