| Horsley Ventures Limited | Professional & scientific | 2022 |
| Hot Chocolate Limited | Arts & recreation | 1973 |
| Hot ROD Burgers Kingston Ltd | Wholesale & retail | 2018 |
| Hot Spring Professional Limited | Real estate | 2008 |
| Houndstone Holdings Ltd | Real estate | 2024 |
| House of AA Limited | Professional & scientific | 2025 |
| House of Beauty Acadamy Ltd | Other services | 2022 |
| House of Ruby Ltd | Wholesale & retail | 2025 |
| House Whisperer Ltd | Information & communication | 2010 |
| Housesbymetnil Ltd | Real estate | 2024 |
| HOW NOW Brown COW Limited | Information & communication | 2026 |
| Howbury Ltd | Real estate | 2014 |
| Howell-Jones LLP | | 2007 |
| Howell-Jones Partnership Limited | Professional & scientific | 1988 |
| Hoyea Ltd | Hospitality | 2018 |
| Hoyport Limited | Extraterritorial | 1985 |
| HPE UK Healthcare and Education Ltd | Wholesale & retail | 2018 |
| HR Bridge Consulting Limited | Professional & scientific | 2017 |
| HR Heating & Plumbing Ltd | Construction | 2020 |
| HR Mobile Tyres Ltd | Wholesale & retail | 2026 |
| Hrprop Limited | Administrative & support | 2009 |
| HS Clinical Consulting Limited | Professional & scientific | 2022 |
| HSA Locums Ltd | Administrative & support | 2017 |
| HSJ Cleaning Limited | Administrative & support | 2017 |
| HTS Hardy Tree Surgeons Ltd | Administrative & support | 2023 |
| HUA Xuan Ltd | Real estate | 2021 |
| Huah Limited | Professional & scientific | 2012 |
| Huayue UK Ltd. | Wholesale & retail | 2020 |
| Hulls Landscapes Limited | Administrative & support | 2015 |
| Human Wonder UN Limited | Health & social care | 2021 |
| HUMANITY.50 Ltd | Professional & scientific | 2026 |
| Huntingdon Place Management Limited | Real estate | 2015 |
| Huriya Ltd | Financial services | 2019 |
| Hurston Holdings Ltd | Financial services | 2025 |
| HUW Arthur Limited | Professional & scientific | 2014 |
| HW Property Investment Limited | Real estate | 2021 |
| Hybsa Consulting Limited | Professional & scientific | 2022 |
| Hydrazine Ltd | Wholesale & retail | 2017 |
| Hyphame Facility Company Ltd | Real estate | 2025 |
| Hythe Bridge Partners Ltd | Administrative & support | 2016 |
| HZH Enterprises Ltd | Wholesale & retail | 2026 |
| I Heart Nails Ltd | Other services | 2019 |
| I. D. S. L. Supplies Limited | Wholesale & retail | 2001 |
| I.A.M Ebikes Ltd. | Wholesale & retail | 2025 |
| I12LEARN Limited | Education | 2012 |
| Iamme Recordings Limited | Arts & recreation | 2013 |
| IAN Humphrey Creative Limited | Professional & scientific | 2015 |
| Iata Ltd | Health & social care | 2020 |
| IBC TV Limited | Information & communication | 2003 |
| Icon Consulting Group Limited | Professional & scientific | 2001 |
| Icon International Services Limited | Professional & scientific | 1996 |
| ICS TM Ltd | Administrative & support | 2013 |
| Icyco Ltd | Energy | 2021 |
| Icytea Limited | Administrative & support | 2009 |
| Idea Centric Ltd | Professional & scientific | 2022 |
| Idea Consulting Ltd | Information & communication | 2022 |
| Identiworks Ltd | Information & communication | 2026 |
| IDG Trustees Limited | Other services | 2020 |
| IDL MGM Ltd | Professional & scientific | 2017 |
| Idlehurst Asset Management Ltd | Real estate | 2020 |
| IDR Consulting Limited | Information & communication | 2005 |
| Idsl Limited | Other services | 2015 |
| IF X Then Y Limited | Professional & scientific | 2024 |
| IFA Support Limited | Other services | 2004 |
| Ifaster Limited | Real estate | 2022 |
| Ifis Limited | Professional & scientific | 1989 |
| Ig-Smart Ltd | Information & communication | 2009 |
| IGS American Limited | Wholesale & retail | 2013 |
| Iipmis Ltd | Information & communication | 2026 |
| IIS 2019 Ltd | Construction | 2019 |
| IJS Publishing Group Limited | Information & communication | 2003 |
| IL Forno Volante Limited | Hospitality | 2022 |
| IM Cloud Consultants Ltd | Information & communication | 2023 |
| Images in Order Limited | Information & communication | 2022 |
| Imaginal Intelligence Ltd | Extraterritorial | 2025 |
| Imagine Communications Emea (UK) Ltd. | Information & communication | 2012 |
| IMAGING360ACADEMY Ltd | Education | 2026 |
| Imani Software Solutions Limited | Information & communication | 2015 |
| Imba London Ltd | Hospitality | 2022 |
| Imber Place (Thames Ditton) Management Company Limited | Households | 2008 |
| IMD Property Solutions Limited | Construction | 2017 |
| Imiara Ltd | Health & social care | 2025 |
| Imind Business Consulting Limited | Professional & scientific | 2024 |
| Immense Impact Ltd | Professional & scientific | 2026 |
| Imonitor Holdings Ltd | Information & communication | 2023 |
| Impact Kinetics Ltd | Extraterritorial | 2018 |
| Imperial Homes & Developments Limited | Construction | 2013 |
| IN Demand Associates Ltd | Administrative & support | 2009 |
| IN Demand Opportunities Group Limited | Administrative & support | 2008 |
| IN Key Solutions Limited | Information & communication | 2015 |
| In-Thebox.Co.Uk Limited | Manufacturing | 2009 |
| Incalmo Architects Limited | Professional & scientific | 2012 |
| Incipere Enterprise Ltd | Information & communication | 2019 |
| Incisive Accounting Limited | Professional & scientific | 2010 |
| Incite Fitness Limited | Information & communication | 2020 |
| Incite OUT Limited | Professional & scientific | 2004 |
| Increment Strategy Ltd | Professional & scientific | 2026 |
| Incubator Project Innovations Limited | Wholesale & retail | 2023 |
| Independent Architects Limited | Professional & scientific | 2005 |
| Indie Visuals ME Limited | Information & communication | 2015 |