| Hymax Company Limited | Wholesale & retail | 2020 |
| Hype Partners Ltd | Professional & scientific | 2016 |
| Hypecrew Ltd | Wholesale & retail | 2025 |
| Hypelutu Ltd | Professional & scientific | 2025 |
| Hypenext Online Ltd | Wholesale & retail | 2026 |
| Hyper Construction Ltd | Construction | 2018 |
| Hyper Group International Ltd | Wholesale & retail | 2018 |
| Hyperionworks Ltd | Professional & scientific | 2019 |
| Hyperjet Aerospace Limited | Transport & logistics | 2017 |
| Hyperland L.P. | | 2016 |
| Hypersonicworks Ltd | Manufacturing | 2024 |
| Hypertrend Limited | Wholesale & retail | 2025 |
| Hypervox Limited | Wholesale & retail | 2021 |
| Hypesware Ltd | Wholesale & retail | 2023 |
| Hypez Ltd | Wholesale & retail | 2021 |
| Hypnos Infinitum Limited | Hospitality | 2019 |
| Hyrax Resourcing Ltd | Administrative & support | 2014 |
| Hythe Road Stores Ltd | Wholesale & retail | 2011 |
| HYW Tech Ltd | Information & communication | 2025 |
| Hywel John Surveys Limited | Administrative & support | 2006 |
| HZ Design Solutions Ltd | Administrative & support | 2019 |
| Hzaben for Media & Education Support Limited | Information & communication | 2020 |
| Hzeegrow Limited | Education | 2025 |
| HZL Luxury Cars Ltd | Wholesale & retail | 2010 |
| I & D Properties Limited | Real estate | 2005 |
| I & I Holdings Ltd | Real estate | 2019 |
| I & PA Cleaning Services Limited | Administrative & support | 2022 |
| I & Z Limited | Water & waste | 2012 |
| I AM by Katherine Ferguson Ltd | Other services | 2018 |
| I AM Source Ltd | Wholesale & retail | 2025 |
| I Cleaner Domestic and Commercial Ltd | Administrative & support | 2015 |
| I D S Security Systems Limited | Administrative & support | 1996 |
| I Drive Automotive Ltd | Wholesale & retail | 2018 |
| I Drive Driver Training Ltd | Education | 2018 |
| I EAT Tomatoes Media Limited | Professional & scientific | 2025 |
| I Electrician & Renewables Ltd | Construction | 2021 |
| I G Build Ltd | Construction | 2023 |
| I H a Properties Limited | Real estate | 2020 |
| I H Crystal Blue Technology Limited | Information & communication | 2015 |
| I Khan Investments Limited | Real estate | 2021 |
| I Love Food Limited | Hospitality | 2009 |
| I Love YOU Group Limited | Wholesale & retail | 2020 |
| I LUV Coffee Limited | Hospitality | 2009 |
| I M Investments (London) Ltd | Real estate | 2017 |
| I Malik Building Ltd | Other services | 2025 |
| I P Glass Limited | Construction | 2019 |
| I Q Flooring Ltd | Wholesale & retail | 2015 |
| I R Davies Media Limited | Information & communication | 2019 |
| I R Parkin Limited | Health & social care | 2013 |
| I S Construction Limited | Construction | 2013 |
| I Teach (Wales) Limited | Education | 2012 |
| I Valentin Limited | Transport & logistics | 2017 |
| I&J Co. Ltd | Transport & logistics | 2026 |
| I&S Communications Ltd | Wholesale & retail | 2017 |
| I&S International Ltd | Wholesale & retail | 2022 |
| I+M Limited | Administrative & support | 2006 |
| I-Act for Positive Mental Health and Wellbeing Ltd | Education | 2018 |
| I-Angel Consulting Ltd | Construction | 2011 |
| I-Dea Solutions Ltd | Professional & scientific | 2010 |
| I-Learn 2 Earn Ltd | Education | 2021 |
| I-Tea & Peking Bakery Ltd | Hospitality | 2019 |
| I.Anka-Eo Ltd | Manufacturing | 2019 |
| I.F.D.H.P Limited | Wholesale & retail | 2019 |
| I.Lase Ltd | Health & social care | 2012 |
| I.M.P. (Trading) Limited | | 1982 |
| I.M.T Ceramics Ltd | Construction | 2016 |
| I.S.S.E.T. (Training) Limited | Education | 2001 |
| I.T. Enviro Logic Limited | Professional & scientific | 2006 |
| I.T.M. Head Wrightson Teesdale Limited | | 1984 |
| I.T.S Catering Ltd | Hospitality | 2015 |
| I.W.F Roofing & Cladding Services Ltd | Construction | 2011 |
| I4SPORTS Ltd | Wholesale & retail | 2020 |
| I54 Ltd | Real estate | 2016 |
| IA Building Construction Ltd | Extraterritorial | 2019 |
| IA Ventures Ltd | Wholesale & retail | 2025 |
| IA Wellness Limited | Other services | 2017 |
| Iaaaa Ltd | Wholesale & retail | 2023 |
| Iaaeauk Ltd | Wholesale & retail | 2025 |
| IAE Hire Ltd | Construction | 2022 |
| IAH Enterprise Limited | Health & social care | 2025 |
| Iain Davison Limited | Administrative & support | 2012 |
| Iairshop Ltd | Professional & scientific | 2007 |
| Ialta Holdings Ltd | Financial services | 2025 |
| IAM London Ltd | Transport & logistics | 2019 |
| Iamas Technologies Ltd | Professional & scientific | 2019 |
| Iamgo Limited | Professional & scientific | 2018 |
| IAN Bebb Limited | Professional & scientific | 2019 |
| IAN Bell Group Ltd | Real estate | 2020 |
| IAN Butterworth Holdings Ltd | Real estate | 2022 |
| IAN Butterworth Ltd | Administrative & support | 2017 |
| IAN Collins Constructions Limited | Administrative & support | 2019 |
| IAN Coughtrey & SON Heating and Plumbing Limited | Construction | 2021 |
| IAN Dando Architectural Services Ltd | Professional & scientific | 2021 |
| IAN Pardoe Limited | Health & social care | 2021 |
| IAN Parfitt Consulting Ltd | Administrative & support | 2014 |
| Iancu Quality Ltd | Manufacturing | 2025 |
| Iappmanager Limited | Information & communication | 2012 |
| Iara Ltd | Manufacturing | 2007 |
| IAS Construction & Maintenance Limited | Construction | 2017 |
| IB & IB Tech Solutions Ltd | Information & communication | 2020 |