| Hornby Ventures Limited | Professional & scientific | 2025 |
| Horscroft Turner Byrne & Co Limited | Professional & scientific | 2018 |
| Host With Style Rentals Ltd | Hospitality | 2023 |
| Hot Air POD Limited | Professional & scientific | 2018 |
| Hot Bean Ltd | Hospitality | 2024 |
| Hotelwc Ltd | Administrative & support | 2018 |
| Hoth Holdings Limited | Real estate | 2021 |
| HOU Sheng UK Limited | Wholesale & retail | 2007 |
| Houghton Westville Partners Limited | Professional & scientific | 2017 |
| Houlton Human Resources Consulting Limited | Professional & scientific | 2006 |
| Hounslow Coachworks Limited | Wholesale & retail | 2009 |
| Hounslow Heating & Plumbing Supplies Limited | Wholesale & retail | 1998 |
| Hounslow Meat Store Limited | Wholesale & retail | 2011 |
| Hounslow Thakers Ltd | Hospitality | 2023 |
| House of Hardys Ltd | Wholesale & retail | 2021 |
| House of JAM Ltd | Real estate | 2018 |
| House of Pneuma Limited | Real estate | 2024 |
| House of Scaffolding Ltd | Construction | 2017 |
| Housing Solutions London Ltd | Real estate | 2020 |
| Hoverla UA Ltd | Administrative & support | 2019 |
| Howarth Rose Investing Ltd | Real estate | 2022 |
| Howler Monkey Ltd | Information & communication | 2007 |
| Howzit Heating Ltd | Construction | 2021 |
| HPK Commodities Ltd | Wholesale & retail | 2025 |
| Hrmundy Consulting Ltd | Professional & scientific | 2016 |
| HS Academy Ltd | Education | 2022 |
| HS Holdings Ltd | Real estate | 2026 |
| HS Professional Learning Ltd | Education | 2023 |
| Hsas Services Limited | Professional & scientific | 2019 |
| Hsbk Property Investments Ltd | Real estate | 2017 |
| Hshatton Ltd | Wholesale & retail | 2024 |
| HT Cafe Limited | Hospitality | 2023 |
| Hthmedia Ltd | Professional & scientific | 2023 |
| Hueyt Ltd | Information & communication | 2019 |
| Humble Children Limited | Wholesale & retail | 2021 |
| Hummingbird Coaching Ltd | Health & social care | 2021 |
| Humphrey & Crane Limited | Information & communication | 2018 |
| Huns Global Service Limited | Information & communication | 2016 |
| Huntington Digital Ltd | Information & communication | 2024 |
| Hush Homes Ltd | Real estate | 2014 |
| Hydra Development Ltd | Real estate | 2022 |
| Hyperring Alliance Ltd | Information & communication | 2025 |
| Hytron Limited | Construction | 2024 |
| HZA Holdings Limited | Real estate | 2026 |
| I-Wood Products Ltd | Wholesale & retail | 2022 |
| IA: Intelligent Acceleration Ltd | Information & communication | 2026 |
| IB & Co Investments Limited | Real estate | 2018 |
| Ibcp Group Ltd | Construction | 2011 |
| Ichi Mart Limited | Wholesale & retail | 2021 |
| Icon Global Sports Agency Ltd | Arts & recreation | 2024 |
| Idcs Solutions Ltd | Professional & scientific | 2023 |
| Idea Scout Ltd | Professional & scientific | 2018 |
| Ideal Link Ltd | Administrative & support | 2007 |
| IDG Commissioning Ltd | Professional & scientific | 2010 |
| Iexpand Consultancy Services Limited | Information & communication | 2018 |
| IF - Inspiring Futures Limited | Education | 2014 |
| IFG London Limited | Construction | 2014 |
| Iforge Limited | Information & communication | 2004 |
| IGA Scaffolding Ltd | Construction | 2022 |
| Ijudge Photography Ltd | Professional & scientific | 2019 |
| Ikigai Consortium Ltd | Wholesale & retail | 2024 |
| IL Gusto Tusha Limited | Hospitality | 2019 |
| ILC Rrmc Holdings Limited | Professional & scientific | 2025 |
| Ilirjan Ltd | Wholesale & retail | 2023 |
| IMP ADR Ltd | Professional & scientific | 2021 |
| Imperial Commercial Ltd | Construction | 2019 |
| Imperial Contracts Ltd | Construction | 2017 |
| Imperial Wholesale UK Limited | Wholesale & retail | 2023 |
| Imperium E-Holdings Ltd | Wholesale & retail | 2026 |
| Imperium Fitness Ltd | Arts & recreation | 2013 |
| Imperium Protection Solutions Ltd | Administrative & support | 2018 |
| Imperium UA Ltd | Wholesale & retail | 2025 |
| Impressive Phone & Vape Ltd | Wholesale & retail | 2023 |
| Impressive Vape&Phone Ltd | Wholesale & retail | 2020 |
| Impulse Vending Co Ltd | Wholesale & retail | 2022 |
| IN OUR Element Ltd | Other services | 2022 |
| IN Space Consult Ltd | Information & communication | 2020 |
| IN Your Face Advertising (Iyfa) Limited | Professional & scientific | 2015 |
| In-Cubed Advisory Services Ltd | Information & communication | 2025 |
| Inbox Warriors Limited | Administrative & support | 2007 |
| Inci G. B. Ltd | Health & social care | 2019 |
| Indianbazaar Limited | Wholesale & retail | 2023 |
| Indigo Consulting London Ltd | Information & communication | 2017 |
| Indus Valley Beverages Limited | Wholesale & retail | 2026 |
| Infinite Atlas Ltd | Information & communication | 2026 |
| Infinite Metric Limited | Transport & logistics | 2020 |
| Infinitee Property Ltd | Real estate | 2023 |
| Inform Advertising Limited | Administrative & support | 2013 |
| Information Quotient Software Services PVT Limited | Information & communication | 2008 |
| Inga Investment Holdings Limited | Professional & scientific | 2024 |
| Ingeni Developments Ltd | Construction | 2016 |
| Inisbiggle Investments Limited | Financial services | 2024 |
| Inklink UK Ltd. | Wholesale & retail | 2002 |
| Inknowation Limited | Professional & scientific | 2014 |
| Inner EYE Productions Limited | Information & communication | 2017 |
| Innovatek Arts Ltd | Information & communication | 2025 |
| Innovation International Limited | Wholesale & retail | 2019 |
| Inside Outside Sales Centre Limited | Information & communication | 2024 |
| Insight in Focus Ltd | Professional & scientific | 2023 |
| Inspiration Designs & Marketing Ltd | Professional & scientific | 2017 |