| Hullsec | Professional & scientific | 2025 |
| Hulse Flooring Limited | Construction | 2017 |
| Humble PIE (Standish) Ltd | Hospitality | 2025 |
| Humphrey-Ths Limited | Other services | 2026 |
| Hunter and Waller Financial Services Ltd | Professional & scientific | 2019 |
| Hunters Plantweld Ltd | Manufacturing | 2016 |
| Huntsfort Limited | Administrative & support | 2007 |
| Hurley Property Group Ltd | Real estate | 2025 |
| Huron Property Investments Limited | Real estate | 2016 |
| Hurst and Wills Limited | Real estate | 2012 |
| Hurst Operations Ltd | Information & communication | 2026 |
| Hurst Property Group Ltd | Real estate | 2017 |
| Hurst Rental Group Ltd | Real estate | 2024 |
| Husnu Limited | Hospitality | 2024 |
| Huwel Ltd | Education | 2018 |
| HW Products Limited | Wholesale & retail | 2018 |
| HWC Brickwork Ltd | Construction | 2018 |
| HWK Properties Ltd | Real estate | 2025 |
| Hydraulic System Services Limited | Professional & scientific | 2025 |
| Hydraworks Ltd | Professional & scientific | 2026 |
| Hydrogen Horizons Limited | Professional & scientific | 2015 |
| Hydrosealmastics Ltd | Construction | 2023 |
| Hykem Limited | | 1973 |
| Hylomar Limited | Manufacturing | 2000 |
| Hype Media Ltd. | Manufacturing | 2018 |
| Hyrex Limited | Wholesale & retail | 2026 |
| Hywh Limited | Wholesale & retail | 2022 |
| I & a Johnson Limited | Professional & scientific | 2004 |
| I C Senior Consultancy Ltd | Professional & scientific | 2015 |
| I D & F Consulting Limited | Information & communication | 2019 |
| I P & K Property Management Ltd | Real estate | 2024 |
| I R Plastering Ltd | Construction | 2018 |
| I&W Properties Group Ltd | Real estate | 2024 |
| I'M Fine Attire Ltd | Wholesale & retail | 2020 |
| I.V.E Associates Ltd | Professional & scientific | 2014 |
| I2I Contracting Ltd | Information & communication | 2020 |
| IAN Lavin Ltd | Wholesale & retail | 2004 |
| IAN Lawson Design Limited | Professional & scientific | 1987 |
| IAN Livesey Artwork Limited | Wholesale & retail | 2026 |
| IAN Lucas Security Shutters Limited | Manufacturing | 2007 |
| IAN Ratcliffe Inspection Services Ltd | Professional & scientific | 2017 |
| Ianis ANA Logistics Ltd | Transport & logistics | 2015 |
| IAW Projects Limited | Construction | 2025 |
| Ibex International Limited | Wholesale & retail | 2023 |
| IBO Barber Shop Ltd | Other services | 2025 |
| Ice Arena (Wales) Limited | Arts & recreation | 2012 |
| Ice HCW Limited | Wholesale & retail | 2019 |
| ICL Education & Training Ltd | Administrative & support | 2023 |
| ICL Site Services Limited | Professional & scientific | 2017 |
| ICS Industrial Concreting Solutions Ltd | Construction | 2025 |
| ICT Solutions Hub Ltd | Information & communication | 2025 |
| Idea Consult Limited | Professional & scientific | 2021 |
| Ideal Spaces Ltd | Real estate | 2022 |
| Idefence Limited | Information & communication | 2018 |
| Idem Safety Switches Limited | Manufacturing | 2003 |
| Identity Collective Ltd | Wholesale & retail | 2025 |
| Identity Life Ltd | Arts & recreation | 2007 |
| Identity Office Ltd | Real estate | 2007 |
| IDK Transport Ltd | Transport & logistics | 2025 |
| Idle Letters Ltd | Professional & scientific | 2018 |
| IEC Consulting Ltd | Manufacturing | 2013 |
| Ifeanyi Chukwu Ltd | Real estate | 2023 |
| IG Trdares Online Ltd | Wholesale & retail | 2019 |
| Igbo Progressive Union Wigan and Leigh CIC | Other services | 2025 |
| Ignite Asset Management Limited | Administrative & support | 2018 |
| Ignite Sports UK PTY Limited | Professional & scientific | 2021 |
| Igpp Limited | Education | 2020 |
| IHK Holdings Ltd | Real estate | 2016 |
| IIW Electrical Ltd | Construction | 2022 |
| IJ Installationav Ltd | Construction | 2026 |
| Ijal Ltd | Wholesale & retail | 2020 |
| IKO Holdings Limited | Financial services | 1989 |
| IKO PLC | Manufacturing | 1992 |
| IKO U.K. Limited | Financial services | 1999 |
| ILK Studio Limited | Professional & scientific | 2008 |
| Ilove Snacks Ltd | Manufacturing | 2024 |
| Ilovemygardenbuilding Ltd | Manufacturing | 2025 |
| Ilpadrinonasu Ltd | Hospitality | 2025 |
| IM Carriers Ltd | Transport & logistics | 2025 |
| Image Dental Laboratory Ltd | Manufacturing | 2024 |
| Image Joinery Projects Ltd | Manufacturing | 2015 |
| Imagination Images Limited | Professional & scientific | 2025 |
| Imagine Collective Ltd | Arts & recreation | 2025 |
| Imarni Construction Network Ltd | Construction | 2011 |
| IMC Transport Limited | Professional & scientific | 2018 |
| Imca International Holding Ltd | Professional & scientific | 2026 |
| Imerge Solutions Limited | Information & communication | 2013 |
| IMF Sprinklers Ltd | Administrative & support | 2017 |
| IMJ Connect Ltd | Transport & logistics | 2023 |
| IMJ Haulage Ltd | Transport & logistics | 2006 |
| Immaculate Visionz Ltd | Health & social care | 2015 |
| Imondas | Professional & scientific | 2026 |
| Imosav | Professional & scientific | 2023 |
| Impact Community Group | Education | 2021 |
| Impact Landscape Ltd | Administrative & support | 2025 |
| Impact Media & PR Ltd | Information & communication | 2019 |
| Impactful Community CIC | Other services | 2025 |
| Impeccable Inns Ltd | Professional & scientific | 2020 |
| Impera Global Ltd | Wholesale & retail | 2026 |
| Implemented AI Ltd | Information & communication | 2025 |