| Herne Consultants Limited | Professional & scientific | 1996 |
| Herne Enterprises Limited | Professional & scientific | 1999 |
| HEVER06 Limited | Financial services | 2007 |
| Hidden Britain Tours Limited | Administrative & support | 2005 |
| Hide-Smith Associates Limited | Arts & recreation | 1994 |
| Highbury First Class Glazing Limited | Construction | 2007 |
| Highways and Construction Training Ltd | Construction | 2023 |
| Hildon Limited | Manufacturing | 1984 |
| Hillbliss Limited | Real estate | 2003 |
| Hillcroft Builders Limited | Construction | 2005 |
| Hillier Garden Centres Limited | Wholesale & retail | 2005 |
| Hillsgate Consulting Limited | Professional & scientific | 2004 |
| Hillside Court Management Limited | Other services | 1992 |
| Hindhead Music Centre Limited | Education | 1996 |
| Hodl Rally Ltd | Administrative & support | 2018 |
| Hoi's Chinese Takeaway Ltd | Hospitality | 2022 |
| Holme Sand & Ballast LLP | | 2006 |
| Holmwood Property Services & Management Limited | Real estate | 2004 |
| Holymoor Limited | Real estate | 2011 |
| Home Comforts Interiors Limited | Manufacturing | 2003 |
| Home Nursing Supplies (Hayling Island) Limited | Wholesale & retail | 2006 |
| Homewood Chiropractic (Fareham) Ltd | Health & social care | 2001 |
| Hook Carpets Limited | Wholesale & retail | 2002 |
| Horizons Aviation Limited | Information & communication | 2004 |
| Horton Scaffolding Limited | Construction | 2002 |
| Horus Systems Limited | Administrative & support | 1986 |
| House Mail Order Limited | Wholesale & retail | 1996 |
| House of Habitat Ltd | Wholesale & retail | 2017 |
| Howes Precision Hydraulics (Holdings) Limited | Professional & scientific | 2003 |
| HTS Associates Limited | Other services | 2002 |
| Hubbard & Clarke Ltd | Public administration | 2018 |
| Hughton Developments Ltd | Real estate | 2018 |
| Huhtamaki Foodservice Portsmouth Limited | Manufacturing | 2017 |
| Huhtamaki Limited | Financial services | 1984 |
| Huhtamaki Metallized Products (USA) Limited | Professional & scientific | 1986 |
| Hull Hampshire Estates & Investments Limited | Financial services | 2003 |
| Hunt Bearings International Ltd | Wholesale & retail | 1993 |
| Huntcourt Properties Limited | Real estate | 2020 |
| Hutchings Consulting Limited | Professional & scientific | 2003 |
| Hythe Engineering Limited | Manufacturing | 2005 |
| I & I Carpentry Limited | Construction | 2003 |
| I.C.E.E Management Holdings Limited | Administrative & support | 2006 |
| I.C.E.E. Managed Services Limited | Information & communication | 2002 |
| IAN Garforth Assets Ltd | Administrative & support | 2019 |
| IAN Garforth Commercial Decorating Ltd | Construction | 2019 |
| IAN Good Limited | Information & communication | 1994 |
| IAN Smith Builders Limited | Construction | 2008 |
| ICL Worldwide Limited | Professional & scientific | 1999 |
| Icode Systems Limited | Information & communication | 1997 |
| ICW Construction Limited | Wholesale & retail | 2002 |
| Image Design Associates Limited | Information & communication | 2003 |
| Imagewrite Limited | Other services | 2001 |
| Imagination Displays Limited | Manufacturing | 2004 |
| Imet Two Limited | | 1907 |
| Impact Express Wholesale Limited | Transport & logistics | 2005 |
| Impact Signs Limited | Administrative & support | 2003 |
| Imperial Hotel (Llandudno) Limited | Hospitality | 1920 |
| In-Depth Analysis Limited | Information & communication | 2007 |
| Independent Ductwork Limited | Manufacturing | 1992 |
| Indo Impex Ltd | Wholesale & retail | 2020 |
| Industrial (Boiler & Contract) Services Limited | Construction | 1982 |
| Industrial Sewn Products Limited | Construction | 1992 |
| Ineos ABS (UK) Limited | Professional & scientific | 2007 |
| Ineos Chemicals South Holdings Limited | Professional & scientific | 2025 |
| Ineos China Holdings III Limited | Professional & scientific | 2022 |
| Ineos European Holdings Limited | Professional & scientific | 2004 |
| Ineos Grangemouth Holdings Limited | Professional & scientific | 2025 |
| Ineos Holdings International Limited | Professional & scientific | 2000 |
| Ineos Investments International Limited | Professional & scientific | 2000 |
| Ingleland Holdings Limited | Real estate | 1994 |
| Inigo Bankrupts Assets Limited | Administrative & support | 2009 |
| Inmar Electrical Ltd. | Manufacturing | 1996 |
| Inmar Limited | Manufacturing | 1998 |
| Inmedia Communications (Holdings) Limited | Information & communication | 1992 |
| Inmedia Communications Group Limited | Information & communication | 2004 |
| Inmedia Communications Limited | Administrative & support | 2004 |
| Innervision Salon Limited | Other services | 2004 |
| Insignant Limited | Wholesale & retail | 1979 |
| Inskip Yachting Ltd | Other services | 2022 |
| Inspire Training and Consultancy Limited | Professional & scientific | 1999 |
| Instant Fabrications Limited | Manufacturing | 1982 |
| Intanda Limited | Information & communication | 2007 |
| Intech Support Limited | Administrative & support | 2001 |
| Integra International Graphics Machinery Ltd. | Extraterritorial | 1990 |
| Integrated Custom Automated Solutions Limited | Information & communication | 2000 |
| Integrated Solutions Corporation Limited | Professional & scientific | 1999 |
| Integrated Systems Management Ltd | Professional & scientific | 2002 |
| Inter-Franc (Golf) Limited | Arts & recreation | 1989 |
| Intereurope Communications Limited | Professional & scientific | 1994 |
| Intereurope Creative Graphics Limited | Extraterritorial | 1998 |
| Intereurope Engineering Design Consultants Limited | Extraterritorial | 1977 |
| Intereurope Holdings Limited | Extraterritorial | 1977 |
| Intereurope Limited | Professional & scientific | 1971 |
| Intereurope Regulations Limited | Extraterritorial | 1998 |
| Intereurope Technology Services Ltd | Extraterritorial | 1986 |
| Intereurope Translations Limited | Extraterritorial | 1995 |
| Interface Professional Services Limited | Information & communication | 2006 |
| Interior Workshop Limited | Professional & scientific | 2007 |
| International Cable Protection Committee Limited | Administrative & support | 2005 |
| International Electrical Investments Limited | Financial services | 2021 |