| Haylock Farming Partnership LP | | 2020 |
| Hazelhurst Management Limited | Information & communication | 1996 |
| HBC Designs & Installations Ltd | Administrative & support | 2014 |
| HCF Art Transportation Ltd | Transport & logistics | 2025 |
| HCF Storage Facility Ltd | Transport & logistics | 2024 |
| HCF Transportation Limited | Transport & logistics | 2024 |
| Headline Photo Limited | Professional & scientific | 2002 |
| Heavenly Frames Limited | Professional & scientific | 2025 |
| Helions Autos Limited | Wholesale & retail | 2024 |
| Hemisphere (Home Improvements) Limited | Wholesale & retail | 1987 |
| Henderson Young Limited | Professional & scientific | 2016 |
| Herbert Retail Ltd | Information & communication | 2025 |
| Herbert Service Ltd | Manufacturing | 2014 |
| Herma UK Limited | Manufacturing | 1991 |
| HF Procurement Limited | Professional & scientific | 2023 |
| Hidayah Group Limited | Wholesale & retail | 2024 |
| Higher Resonance Ltd | Information & communication | 2025 |
| Highfield Assessments Ltd | Health & social care | 2014 |
| Hightech Window Cleaning Ltd | Other services | 2014 |
| Hill Side Catering (2022) Ltd | Hospitality | 2022 |
| Hobbs and Westwood Developments Ltd | Construction | 2025 |
| Hold My Plate Ltd | Wholesale & retail | 2025 |
| Holiday Guides to England Limited | Administrative & support | 2005 |
| Holistic Analytics UK Ltd | Professional & scientific | 2026 |
| Holt and Tide Ltd | Construction | 2025 |
| Homeco Internet Property Ltd. | Information & communication | 2000 |
| Honeytree Education Ltd | Education | 2018 |
| House FIX Property Maintenance Ltd | Construction | 2025 |
| Howard Systems Ltd | Other services | 2020 |
| Howarth Interiors Limited | Manufacturing | 2025 |
| Hsac Group Limited | Wholesale & retail | 2026 |
| Hughes Building Company Limited | Construction | 2001 |
| Hundon Consulting Ltd | Professional & scientific | 2014 |
| Hunky Dory Foods Ltd | Wholesale & retail | 2015 |
| Hvac-Controls Ltd | Professional & scientific | 2012 |
| HVL Pharma UK Ltd | Manufacturing | 1981 |
| Hyperloop Innovations UK Ltd | Professional & scientific | 2022 |
| I D C Insulation Ltd | Construction | 1985 |
| I&K Property Limited | Real estate | 2025 |
| Ibma UK Ltd | Other services | 2022 |
| Ice Electrical Solutions Ltd | Construction | 2022 |
| Ickle Boutique Ltd | Manufacturing | 2022 |
| Ickle Ventures Ltd | Wholesale & retail | 2025 |
| Ignite Umbrella Ltd | Professional & scientific | 2025 |
| Ignitum Ltd | Manufacturing | 2023 |
| Ignyt Fitness Ltd | Arts & recreation | 2023 |
| Igv&S Ltd | Construction | 2015 |
| Ihurteverywhere Ltd | Education | 2023 |
| Iinvest Solutions Ltd | Information & communication | 2023 |
| Ilford Food and Grocery Ltd | Wholesale & retail | 2023 |
| IMD Freight Ltd | Transport & logistics | 2025 |
| Immediate Smiles Ltd | Health & social care | 2021 |
| Indigo Commercial Services Ltd | Construction | 2017 |
| Induction Furnaces Limited | Manufacturing | 2011 |
| Infinity 28 Hair and Beauty Limited | Other services | 2019 |
| Innerspec Technologies UK Ltd | Professional & scientific | 2020 |
| Inspire and Transform Consultancy Limited | Health & social care | 2015 |
| Integrative Approaches Limited | Health & social care | 2015 |
| Inteliheat Ltd | Financial services | 2025 |
| International Beauty Experts Limited | Wholesale & retail | 2020 |
| International Flavours & Fragrances (Pension Trustees) Limited | Extraterritorial | 2018 |
| International N&H Manufacturing UK Limited | Manufacturing | 1999 |
| Inuvano Limited | Information & communication | 2014 |
| Ionut Motoasca Ltd | Health & social care | 2018 |
| Ipek Property Ltd | Real estate | 2025 |
| Ipekuk Property Ltd | Real estate | 2025 |
| Ipekuk Supplier Ltd | Wholesale & retail | 2024 |
| Irfan Arif Real Estate Ltd | Real estate | 2024 |
| Irrigation and Water Limited | Water & waste | 2010 |
| Isopod Ltd | Manufacturing | 2023 |
| IVE Logistics Ltd | Transport & logistics | 2022 |
| IX Solutions Consulting Limited | Professional & scientific | 2021 |
| J. Bradnam and Sons Limited | Manufacturing | 1948 |
| J. Simkonis Ltd | Transport & logistics | 2020 |
| J.J. & T.H.Haylock Limited | Agriculture & fishing | 1959 |
| J2 Cleaning Ltd | Administrative & support | 2014 |
| JA Property Lets Ltd | Real estate | 2018 |
| Jackson and Bragg Builders Limited | Construction | 2019 |
| Jackson Installations & Fabrications Limited | Construction | 2012 |
| Jacq & Wills Landscapes Ltd | Administrative & support | 2006 |
| Jadeite Entertainment Limited | Information & communication | 2020 |
| Jakemans Limited | Real estate | 2014 |
| JAL Services Ltd | Information & communication | 2025 |
| James Rule Executive Chauffeur Ltd | Transport & logistics | 2025 |
| Jamie Warner Estate Agents Ltd | Administrative & support | 2017 |
| Jard Design & Consultancy Ltd | Professional & scientific | 2022 |
| Jason Fitzgerald Ltd | Information & communication | 2012 |
| Jaynic (East Anglia) Limited | Real estate | 2021 |
| Jaynic Developments Ltd | Real estate | 2018 |
| Jaynic Investments LLP | | 2008 |
| Jaynic Properties Limited | Construction | 1993 |
| Jaynic Suffolk Park Limited | Real estate | 2016 |
| Jaynic Suffolk Park Logistics Limited | Real estate | 2016 |
| JBH Private Limited | Health & social care | 2022 |
| JBJ UK Construction Ltd | Construction | 2011 |
| JD Homes (East) Ltd | Real estate | 2026 |
| JD Tiling and Property Services Limited | Construction | 2017 |
| JDB Rentals Ltd | Households | 2022 |
| Jesty Capital LLP | | 2010 |
| Jetstreamx Ltd | Professional & scientific | 2024 |