| Hothead Films Limited | Information & communication | 2022 |
| Hothead Minicams Limited | Information & communication | 2011 |
| HOTSPOT247 Ltd | Wholesale & retail | 2026 |
| Hound Dog Adventures Limited | Other services | 2016 |
| House-Shares Management Limited | Real estate | 2013 |
| Hovemist Limited | Administrative & support | 2003 |
| Howard Cole Gardens Residents Management Company Limited | Households | 2018 |
| Howard Jones Communications Limited | Professional & scientific | 2025 |
| Howett-Thorpe Recruitment Consultants Limited | Administrative & support | 1988 |
| Howgate Homes Ltd | Construction | 2025 |
| Hoyersolutions Limited | Professional & scientific | 2026 |
| HP Alexandra Properties Limited | Real estate | 2022 |
| HP Alfred Properties Limited | Real estate | 2022 |
| HP Carlton 49 DS Properties Limited | Real estate | 2022 |
| HP Granary Properties Limited | Real estate | 2022 |
| HP Grange Properties Limited | Real estate | 2022 |
| HP Residents (East Horsley) Limited | Real estate | 2007 |
| HP Robert 34 DS Properties Limited | Real estate | 2022 |
| HPH Town and Country Limited | Construction | 2017 |
| HQ Building Newfoundland Road Residents Management Company Ltd | Households | 2022 |
| HQ Landscape Construction Ltd | Administrative & support | 2021 |
| Hrimfaxi Limited | Information & communication | 2014 |
| HSG Southsea Limited | Real estate | 2021 |
| HTS Roofing Ltd | Construction | 2019 |
| Http Functions Ltd | Information & communication | 2022 |
| Hudson Honey Ltd | Agriculture & fishing | 2023 |
| Huguenot Editions Limited | Wholesale & retail | 2012 |
| Human Ethical Relationship Company Ltd | Information & communication | 2025 |
| Hummingbird London Limited | Wholesale & retail | 2012 |
| Humphreys Group Holdings Limited | Financial services | 2026 |
| Humphreys Property Investments Ltd | Real estate | 2023 |
| Humphreys Tarmacing Services Ltd | Construction | 2020 |
| Hundred Media Ltd | Professional & scientific | 2017 |
| Hunter Bourne Limited | Administrative & support | 2026 |
| Hunter Daniel Limited | Information & communication | 2008 |
| Huntingford Camping Limited | Hospitality | 2022 |
| Hurlands Ltd | Arts & recreation | 2024 |
| Hurlingham Osteopathy Limited | Health & social care | 2017 |
| Hurricane Capital Advisors UK Limited | Financial services | 2024 |
| Hurstmount Limited | Professional & scientific | 1997 |
| Hutch Associates Limited | Professional & scientific | 2016 |
| Hutchins Property Management Limited | Real estate | 2012 |
| Hydra Management Limited | Information & communication | 1994 |
| Hyltec Limited | Professional & scientific | 2018 |
| HYP3D Ltd | Professional & scientific | 2024 |
| Hyped Marketing Ltd | Professional & scientific | 2016 |
| Hyper Logical Limited | Extraterritorial | 2025 |
| Hyper Network Group Limited | Information & communication | 2024 |
| I Choose Freedom Charity | Health & social care | 1984 |
| I Drew This Ltd. | Professional & scientific | 2016 |
| I P G Associates Limited | Information & communication | 1998 |
| I-4BUSINESS Emea Ltd | Administrative & support | 2017 |
| I-4BUSINESS Group Ltd | Financial services | 2019 |
| I-Blason UK Ltd | Wholesale & retail | 2013 |
| I.T. Contract Management Limited | Information & communication | 1992 |
| I.T. Selection Ltd | Real estate | 2000 |
| I4R Ltd | Real estate | 2014 |
| IAN Bishop Design Limited | Arts & recreation | 1998 |
| IAN Clarke Consultancy Ltd | Information & communication | 2026 |
| IAN Haughton Limited | Administrative & support | 2011 |
| IAN Johnson Associates Limited | Administrative & support | 1986 |
| IAN King Building & Decorating Contractor Limited | Construction | 2003 |
| IAN Livingstone Music Limited | Information & communication | 2011 |
| IAN Penycate Upholstery Limited | Other services | 2015 |
| Ianthine Consulting Ltd | Professional & scientific | 2022 |
| Ichiro AI Ltd | Professional & scientific | 2019 |
| ICM Building Limited | Construction | 2016 |
| Icom Digital Limited | Information & communication | 2017 |
| Icongrove Limited | Construction | 1986 |
| Ideal Property Management Limited | Real estate | 1982 |
| Identity Centre Ltd | Administrative & support | 2015 |
| Ifba Limited | Arts & recreation | 2016 |
| Igedapt Ltd | Professional & scientific | 2025 |
| Ignite Business Partners Limited | Education | 2020 |
| Ignite Coaching Consultancy Ltd | Professional & scientific | 2026 |
| Ignite GAS and Heating Ltd | Construction | 2021 |
| IJ Health Consulting Ltd | Health & social care | 2022 |
| IJ Support Limited | Public administration | 2016 |
| IJA Group Limited | Professional & scientific | 2001 |
| IJZ Services Ltd | Transport & logistics | 2025 |
| IK Contact Ltd | Administrative & support | 2014 |
| IK Roundabout Ltd | Information & communication | 2015 |
| Ikon Pumps Holdings Limited | Professional & scientific | 2025 |
| Ikon Pumps Ltd | Other services | 2019 |
| IL Forno at Daniele Ltd | Hospitality | 2024 |
| Ilfabi Cafe Ltd | Hospitality | 2024 |
| Iloveprimrosehill Ltd | Information & communication | 2014 |
| Iloveshopping Trading Limited | Wholesale & retail | 2019 |
| Image Loft Limited | Professional & scientific | 2006 |
| Imagecourt Limited | Real estate | 1996 |
| Imaging Business Machines Limited | Administrative & support | 2004 |
| Imagotech Limited | Information & communication | 2003 |
| IMG Expert Ltd | Information & communication | 2005 |
| Imperial Medica Limited | Health & social care | 2024 |
| Imperium Custodia Ltd | Professional & scientific | 2008 |
| Impressive Carpets Limited | Wholesale & retail | 2012 |
| Impulse Engineering (Holdings) Limited | Professional & scientific | 2007 |
| Impulse Fire Systems Limited | Professional & scientific | 1987 |
| IN Ones Prime Ltd | Manufacturing | 2020 |
| In-Sync Construction Limited | Professional & scientific | 2020 |