| Highview Care Ltd | Health & social care | 2022 |
| Highview Court Luton RTM Company Limited | Households | 2022 |
| Hillside Metal Works Ltd | Professional & scientific | 2025 |
| Hilltop Build UK Limited | Construction | 2019 |
| Hillz Cleanings Limited | Administrative & support | 2025 |
| Hire Loop Recruitment Ltd | Information & communication | 2023 |
| Hita Limited | Real estate | 2023 |
| Hitchins (Hatfield) Limited | Construction | 1968 |
| HJO Limited | Administrative & support | 2016 |
| HL Training&Consulting Ltd | Professional & scientific | 2025 |
| HMM Property Limited | Real estate | 2025 |
| HN Jewels Ltd | Manufacturing | 2025 |
| HN Transport UK Ltd | Construction | 2018 |
| HNL Electrical Contractors Limited | Construction | 2022 |
| HOE Leasing Limited | Administrative & support | 1961 |
| Holistic Independent Social Work Limited | Health & social care | 2022 |
| Holland Bridgeson Chemical Co., Ltd | Mining & quarrying | 2025 |
| Hollis Home Improvements Ltd | Construction | 2003 |
| Hollow Frame Games Ltd | Information & communication | 2026 |
| Holme Creations Limited | Wholesale & retail | 2020 |
| Holmhurst Mews Residential Management Company Limited | Real estate | 2013 |
| Holmwood Leasing Limited | Wholesale & retail | 1994 |
| Holwell Court Management Company (NO2) Limited | Households | 1982 |
| Holy Lama Naturals Ltd | Wholesale & retail | 2010 |
| Home & Partners Limited | Real estate | 2024 |
| Home Services A&A Ltd | Construction | 2018 |
| Hometria Properties Limited | Real estate | 2025 |
| Honey Bakery Ltd | Manufacturing | 2024 |
| Hoop Genius Limited | Information & communication | 2018 |
| Hornbeam Homes Limited | Construction | 2015 |
| Hosking & Corrigan Property Ltd | Real estate | 2022 |
| House & Lifestyle Ltd | Other services | 2021 |
| House of Beardall Ltd | Health & social care | 2023 |
| House of Citadel Ltd | Real estate | 2022 |
| House of Matumbu (HOM) Ltd | Manufacturing | 2020 |
| House of Performance Limited | Professional & scientific | 2021 |
| HP IT Solutions Limited | Information & communication | 2025 |
| HPK Capital Ltd | Professional & scientific | 2021 |
| Hrtvsh Ltd | Information & communication | 2008 |
| HT Town Barber (Hatfield) Ltd | Other services | 2025 |
| HT Town Barber Ltd | Other services | 2025 |
| Hubb Stays Ltd | Hospitality | 2026 |
| Hugo Clips Ltd | Information & communication | 2024 |
| HUI Construction Ltd | Construction | 2025 |
| HUL Trans Ltd | Transport & logistics | 2019 |
| Humanity Works Consultancy Ltd | Professional & scientific | 2020 |
| Humphicc Ltd | Health & social care | 2024 |
| Hunter Devine Architects Limited | Professional & scientific | 2007 |
| Hunter Lola & Co Ltd | Professional & scientific | 2025 |
| Huntington Law Associates Ltd | Professional & scientific | 2025 |
| Hurlingham Gate Residents Management Company Limited | Households | 2013 |
| Hurst Consultancy Limited | Information & communication | 2002 |
| Hutchings Wharf RTM Company Ltd | Households | 2007 |
| HVR Construction Services Ltd | Construction | 2025 |
| Hyde Court Ltd | Construction | 2024 |
| Hyderabad Kitchens T/A Hyderabad Flavours Limited | Hospitality | 2022 |
| Hydn Ltd | Financial services | 2026 |
| Hydraulika Limited | Construction | 2022 |
| Hydrogen Coffee Limited | Extraterritorial | 2023 |
| Hydrogen Coffee Services Ltd | Professional & scientific | 2023 |
| Hydrogen Services Limited | Extraterritorial | 2023 |
| Hykes International Limited | Wholesale & retail | 2025 |
| Hyname Trading Ltd | Wholesale & retail | 2019 |
| Hyperscale Developments Ltd | Construction | 2020 |
| I & J Scaffolding Limited | Construction | 2017 |
| I and ME Ltd | Wholesale & retail | 2000 |
| I C Lloyd Limited | Health & social care | 2003 |
| I Love Countdown Ltd | Wholesale & retail | 2023 |
| I-Point Limited | Wholesale & retail | 2019 |
| I.G. Transport Ltd | Transport & logistics | 2018 |
| I.G.B Transport Ltd | Transport & logistics | 2024 |
| I.M.O. Electronics Limited | Wholesale & retail | 1976 |
| I.M.O. Precision Controls Limited | Manufacturing | 1963 |
| I.O.Academy Limited | Education | 2025 |
| IAS Accountancy & Taxation Services Limited | Professional & scientific | 2018 |
| IB Painting & Decoration Ltd | Construction | 2019 |
| Ice Recruitment Limited | Administrative & support | 2008 |
| ICG Services Limited | Extraterritorial | 1996 |
| Icgl Holdings Ltd | Construction | 2021 |
| Ichina Food Limited | Hospitality | 2022 |
| Iconic Care Services Ltd | Health & social care | 2023 |
| Idea International Projects Limited | Arts & recreation | 2008 |
| Identiti Communication Consultancy Limited | Administrative & support | 2024 |
| Ifor Apparel Ltd | Wholesale & retail | 2025 |
| Ifrc Holdings Limited | Wholesale & retail | 2020 |
| Igbo Hearts CIC | Other services | 2015 |
| Igca Accounting & Financial Services Limited | Professional & scientific | 2024 |
| IGM Labs Ltd | Information & communication | 2026 |
| Ignite Motors Limited | Wholesale & retail | 2025 |
| IJ Real Estate Limited | Real estate | 2022 |
| Ikon Pictures Limited | Professional & scientific | 2002 |
| Illyrian Stones Ltd | Wholesale & retail | 2026 |
| Imassive Limited | Information & communication | 2012 |
| IMB Auto Ltd | Administrative & support | 2020 |
| IMG Consultancy Ltd | Professional & scientific | 2022 |
| Immaculate Pharma & Locum Ltd | Health & social care | 2018 |
| Immersive Fitness Company Ltd | Administrative & support | 2023 |
| IMO Automation Limited | Manufacturing | 2020 |
| IMO Group of Companies Limited | Professional & scientific | 1987 |
| IMO Holdings Ltd | Financial services | 2022 |