| Hydro Heat N Air Ltd | Construction | 2018 |
| Hydro Station Limited | Wholesale & retail | 2008 |
| Hydro-Mech Services Ltd | Construction | 2010 |
| Hydroclean Window Cleaning Ltd. | Administrative & support | 2011 |
| Hydromotion Limited | Extraterritorial | 2021 |
| Hydron Pumps Limited | Energy | 2018 |
| Hydroplumb Ltd | Construction | 2024 |
| Hydropower Bathrooms Ltd | Wholesale & retail | 2018 |
| Hydropower Plumbing & Heating Limited | Construction | 2016 |
| Hydropulse Limited | Energy | 2025 |
| Hydrotech Ltd | Administrative & support | 2017 |
| HYE Catering Ltd | Hospitality | 2023 |
| Hygeia-Pro Ltd | Health & social care | 2023 |
| Hyggs Concierge Limited | Other services | 2019 |
| Hygiene Improvement Solutions Limited | Professional & scientific | 2011 |
| Hygiene-Uk Limited | Wholesale & retail | 2020 |
| Hygienic Plastics Ltd | Wholesale & retail | 2007 |
| Hyivy Health Limited | Manufacturing | 2023 |
| Hylife Coaching Ltd | Education | 2023 |
| Hylton Grange Health Care Limited | Health & social care | 2022 |
| HYM Ventures Ltd | Wholesale & retail | 2023 |
| Hymarnham Power Limited | Manufacturing | 2023 |
| Hyosis Ltd | Professional & scientific | 2025 |
| Hype Dance Company | Arts & recreation | 2004 |
| Hype Salons Limited | Other services | 2025 |
| Hype@Sharrow Limited | Other services | 2025 |
| Hyperactive Events Limited | Hospitality | 2025 |
| Hyperactive World Records Limited | Information & communication | 2025 |
| Hyperlogic Firm Limited | Information & communication | 2025 |
| Hypernest Innovations Ltd | Information & communication | 2025 |
| Hyperscale Consulting Ltd | Information & communication | 2025 |
| Hypnosemantic Ltd | Information & communication | 2025 |
| Hypnotic World Limited | Other services | 2006 |
| Hysol Group Limited | Construction | 2018 |
| Hystri Limited | Information & communication | 2025 |
| HZ Tech Ltd | Financial services | 2018 |
| HZB Investments Limited | Other services | 2019 |
| Hzenterprisesuk Limited | Wholesale & retail | 2025 |
| Hzuaegna Ltd | Wholesale & retail | 2025 |
| HŌM Personal Training Ltd | Arts & recreation | 2025 |
| I & I Travel Media Limited | Information & communication | 2015 |
| I & R Cooper Properties Ltd | Real estate | 2024 |
| I AM Ryan Spence Ltd | Other services | 2021 |
| I and BE Limited | Manufacturing | 2015 |
| I Aslam Ltd | Health & social care | 2025 |
| I Bird Engineering Ltd | Construction | 2009 |
| I C Innovations Limited | Wholesale & retail | 2004 |
| I DID IT My Way Ltd | Other services | 2013 |
| I G Immanuel Limited | Transport & logistics | 2025 |
| I Interiors Limited | Construction | 2007 |
| I Invest Property Development Limited | Construction | 2023 |
| I Know Nothing Ltd | Hospitality | 2018 |
| I Love Cosmetics Limited | Wholesale & retail | 2003 |
| I Love Sweets Ltd | Wholesale & retail | 2025 |
| I M & M Limited | Manufacturing | 1998 |
| I MAX Phone Ltd | Wholesale & retail | 2025 |
| I Mend IT UK Limited | Other services | 2014 |
| I Monster Limited | Administrative & support | 2001 |
| I Power Electrical Ltd | Construction | 2019 |
| I Project Management Services Limited | Professional & scientific | 2026 |
| I R Jones Limited | Health & social care | 2015 |
| I Recycle Ltd | Wholesale & retail | 2019 |
| I Refurb Tech Limited | Wholesale & retail | 2025 |
| I Singh Properties Limited | Real estate | 2016 |
| I Stanulet Ltd | Health & social care | 2013 |
| I&E Plumbing and GAS Ltd | Construction | 2026 |
| I&L Trans Ltd | Transport & logistics | 2015 |
| I'D Love Ltd | Administrative & support | 2017 |
| I-Air Limited | Professional & scientific | 2010 |
| I-Am WOW Ltd | Construction | 2007 |
| I-Bee Technical Advisory Limited | Professional & scientific | 2017 |
| I-Bos (Yorkshire) Ltd | Construction | 2022 |
| I-Bos Holdings Ltd. | Financial services | 2025 |
| I-Bos Interiors Ltd. | Construction | 2013 |
| I-Care Total Solutions Ltd | Construction | 2021 |
| I-Dent Oral Health Care Ltd | Health & social care | 2010 |
| I-Dragoness Ltd | Hospitality | 2024 |
| I-Lectric Limited | Construction | 2019 |
| I-Lectrician Limited | Construction | 2019 |
| I-Safe Limited | Professional & scientific | 2011 |
| I-Squared Investments 2 Limited | Real estate | 2021 |
| I-Squared Investments Limited | Real estate | 2018 |
| I-Team Professional Limited | Wholesale & retail | 2019 |
| I. I. C. Interior Limited | Construction | 2005 |
| I.B Lazer Lounge Ltd | Other services | 2024 |
| I.C.D. Laboratories Limited | Wholesale & retail | 2013 |
| I.E. Elliots Ltd | Hospitality | 2023 |
| I.F.P. Forest and Paper Products (UK) Limited | Wholesale & retail | 1962 |
| I.K.S.M Halal Food Ltd | Wholesale & retail | 2019 |
| I.M.Weddings Ltd | Hospitality | 2022 |
| I.R. Priest & Company Limited | Real estate | 1982 |
| I.R. Smyth and SON Limited | Administrative & support | 2016 |
| I.S. Reynolds Limited | Professional & scientific | 2021 |
| I.S.L. Holdings Limited | Professional & scientific | 2003 |
| I3 Productions Ltd | Wholesale & retail | 2024 |
| I78 Limited | Health & social care | 2010 |
| Iacob Patisserie Limited | Hospitality | 2019 |
| IAE Designs Limited | Professional & scientific | 2024 |
| Iain James Limited | Arts & recreation | 2026 |
| IAM Group Ltd | Financial services | 2025 |