| Hurt Plant Hire Ltd | Financial services | 2020 |
| Hustle Industries Ltd | Wholesale & retail | 2026 |
| Hutchinson Construction Limited | Construction | 2014 |
| Huzzuh Ltd | Information & communication | 2018 |
| HV Beauty Lounge Limited | Other services | 2023 |
| Hylaw Goods Ltd | Wholesale & retail | 2025 |
| Hype! Collective UK Ltd | Administrative & support | 2026 |
| Hysa Leisure Ltd | Other services | 2026 |
| HZR Capital Ltd | Information & communication | 2021 |
| I - Wire Electrical Services Limited | Construction | 2015 |
| I AM Literally a MUG Ltd | Wholesale & retail | 2022 |
| I Care (GB) Limited | Administrative & support | 1994 |
| I Care Extra Care Limited | Health & social care | 2004 |
| I Care Land Development Limited | Construction | 2004 |
| I D Joinery & Building Limited | Construction | 2015 |
| I-Detect Ltd | Other services | 2011 |
| I-Mar Services Limited | Professional & scientific | 2017 |
| I.L. & M.E. Tyson Ltd | Construction | 2003 |
| I.M. Fabrications Limited | Manufacturing | 2001 |
| I.T.M Leisure (Europe) Limited | Wholesale & retail | 2005 |
| I.T.S Valley Ltd | Wholesale & retail | 2025 |
| IAN Donald Logistics Limited | Transport & logistics | 2020 |
| IAN Rose Consulting Ltd | Information & communication | 2015 |
| IAN Watt Accounting Services Limited | Professional & scientific | 2001 |
| Iasos Yachting Ltd | Extraterritorial | 2023 |
| Ibhri Ltd | Health & social care | 2024 |
| Icampus Ltd | Extraterritorial | 2011 |
| Icandi Blackpool Ltd | Wholesale & retail | 2017 |
| Icarus Consultancy Limited | Professional & scientific | 2007 |
| Ice Blue Marine Limited | Extraterritorial | 2024 |
| ICG EBT Limited | Professional & scientific | 2025 |
| Iclkeskills Ltd | Other services | 2023 |
| Icon Darts Events Ltd | Arts & recreation | 2025 |
| Iconnect Change Management Limited | Information & communication | 2013 |
| ICT Deploy & Dispose Limited | Information & communication | 2014 |
| Idea Worldwide Ltd | Arts & recreation | 2011 |
| Ideal Time Limited | Professional & scientific | 2015 |
| IDEAS247 Ltd | Wholesale & retail | 2024 |
| Identity Care Ltd | Health & social care | 2024 |
| Idowebstuff Ltd | Information & communication | 2014 |
| IDS Surfacing Limited | Construction | 2024 |
| IFA Consultancy Limited | Professional & scientific | 2004 |
| Ifor Williams Suppliers Limited | Manufacturing | 2025 |
| IFY N Grant Limited | Health & social care | 2024 |
| Igaf Ltd | Manufacturing | 2024 |
| IH89 Ltd | Information & communication | 2022 |
| II Ivani Ltd | Administrative & support | 2023 |
| Ikatech UK Limited | Other services | 2022 |
| Ikaur-It Ltd | Information & communication | 2018 |
| Ilat Solutions Ltd | Information & communication | 2017 |
| Ilfiniti Limited | Professional & scientific | 2014 |
| Ilfuturo Cafe Limited | Hospitality | 2026 |
| Ilfuturo Holdings Limited | Financial services | 2026 |
| Ilfuturo Kiosk Limited | Wholesale & retail | 2026 |
| Ilfuturo Property Limited | Real estate | 2026 |
| Illuminate Mental Health (Professionals) Limited | Health & social care | 2021 |
| Illuminate Mental Health (UK) Limited | Health & social care | 2021 |
| Illuminate Mental Health Community Interest Company | Health & social care | 2021 |
| Illuminati Surveyors Ltd | Professional & scientific | 2023 |
| Ilyas Consultancy Group Ltd | Information & communication | 2017 |
| IM Lock Stitch Services Limited | Other services | 2020 |
| IMM Access and Inspection Services Ltd | Mining & quarrying | 2018 |
| Imperial Car Wash Ltd | Wholesale & retail | 2021 |
| Imperial Nail and Beauty 3 Ltd | Other services | 2025 |
| Imperial Staffing Solutions Ltd | Wholesale & retail | 2023 |
| Impisi Consulting Ltd | Administrative & support | 2017 |
| Impressed NW Ltd | Other services | 2021 |
| Improve Don’T Move Ltd | Construction | 2019 |
| Impulse Analysis Limited | Professional & scientific | 2018 |
| Impulse Deals Ltd | Wholesale & retail | 2025 |
| IMS Medical Ltd | Health & social care | 2025 |
| IN Community Care Ltd | Health & social care | 2025 |
| In-Portofino Ltd. | Hospitality | 2001 |
| Inchmery Consulting Ltd | Information & communication | 2013 |
| Incognito Bars Limited | Hospitality | 2023 |
| Indaxa Ltd | Financial services | 2019 |
| Inde Retail Ltd | Wholesale & retail | 2024 |
| Indelible INK Tattoo Studio Ltd. | Other services | 2017 |
| Independent Green Access Limited | Information & communication | 2008 |
| Independent Living (North West) Limited | Health & social care | 2001 |
| Indsys Ltd | Information & communication | 2012 |
| Industrial Roofing Blackpool Limited | Construction | 2017 |
| Infinite Loop Events Ltd | Hospitality | 2025 |
| Infinite Safety Ltd | Professional & scientific | 2006 |
| Infinite Technology UK Ltd | Information & communication | 2024 |
| Infinity Labs Limited | Information & communication | 2011 |
| Infios LDN Ltd | Professional & scientific | 2019 |
| Infios U.K. Ltd | Information & communication | 1989 |
| Inflate N Play Leisure Limited | Arts & recreation | 2018 |
| Infobox Limited | Information & communication | 2005 |
| Infobox Reporting Ltd | Administrative & support | 2019 |
| Infogration Ltd | Information & communication | 1999 |
| Infolite Consulting Ltd | Information & communication | 2016 |
| Information for Contracts Ltd | Information & communication | 2013 |
| Infracentral UK Ltd | Information & communication | 2024 |
| Infrachain Technologies Limited | Information & communication | 2025 |
| Inghams Fresh Fish Limited | Hospitality | 2015 |
| Ingleside Enterprise Solutions Ltd | Information & communication | 2014 |
| Ingota Limited | Professional & scientific | 2014 |
| Initiatv Limited | Transport & logistics | 2005 |