| Hotellogic Ltd | Information & communication | 2026 |
| House Share Developments Limited | Construction | 2019 |
| House Share Studios Limited | Real estate | 2019 |
| Howe Hill Farm North Deighton Limited | Agriculture & fishing | 2025 |
| HQE Limited | Information & communication | 2024 |
| HR 180 Ltd | Professional & scientific | 2006 |
| HTF Legal Ltd | Professional & scientific | 2019 |
| Hudson & Hudson Consulting Ltd | Information & communication | 2013 |
| Hudson Kane Ltd | Professional & scientific | 2024 |
| Hudu Limited | Information & communication | 2024 |
| HUE I Ltd | Manufacturing | 2021 |
| HUE Interiors Ltd | Manufacturing | 2020 |
| Hugo Mascie-Taylor Consulting Limited | Professional & scientific | 2020 |
| Hunter Builders (Leeds) Limited | Real estate | 1997 |
| Hunters (Cornworthy) Ltd | Hospitality | 2019 |
| Hydro Brush (UK) Limited | Wholesale & retail | 2008 |
| I D Dunn Limited | Health & social care | 2014 |
| I4 PAY Partners Limited | Professional & scientific | 2005 |
| Iain Henderson Designs Limited | Manufacturing | 2014 |
| IC Music and Apparel Ltd | Wholesale & retail | 2014 |
| Ice Protection Ltd | Financial services | 2025 |
| Iconic Audio Limited | Wholesale & retail | 2018 |
| Identipro Limited | Wholesale & retail | 2009 |
| Idexx Laboratories Limited | Professional & scientific | 1989 |
| Idexx UK Acquisition Limited | Financial services | 2000 |
| IDS Industrial Limited | Professional & scientific | 2020 |
| Ids-Group UK (EOT) Limited | Administrative & support | 2025 |
| Ignition Group Holdings Limited | Financial services | 2022 |
| Ignition Group Limited | Financial services | 2016 |
| Iheat.Me Ltd | Manufacturing | 2020 |
| IIA Construction Services Ltd | Professional & scientific | 2024 |
| Ikoustic Limited | Construction | 2010 |
| Iled Media Ltd | Information & communication | 2024 |
| Illuminating Investments Limited | Construction | 2013 |
| Illumineers Limited | Information & communication | 2026 |
| IM Decor Ltd | Manufacturing | 2023 |
| IMA (Klessmann) UK Ltd | Wholesale & retail | 2006 |
| Imaschelling UK Limited | Manufacturing | 1988 |
| Iminduk Ltd | Health & social care | 2022 |
| Immortalis Ltd | Professional & scientific | 2010 |
| Imperial Works Limited | Real estate | 2020 |
| IMS Building Ltd | Construction | 2024 |
| Inchpebble Ltd | Professional & scientific | 2011 |
| Incus Forge Ltd | Professional & scientific | 2013 |
| Independent Racecourses Consortium LLP | | 2020 |
| Induce Media Limited | Wholesale & retail | 2022 |
| Industrial Coatings Limited | Wholesale & retail | 2015 |
| Industrialised Ltd | Real estate | 2012 |
| Infinity Residential Investments LLP | | 2007 |
| Infosecurity People Limited | Information & communication | 2017 |
| Inger & RAE Limited | Wholesale & retail | 2019 |
| Ingmanthorpe Fold Management Company Limited | Households | 2017 |
| Ingmanthorpe Grange Management Company Limited | Real estate | 2016 |
| Ingmanthorpe Hall Limited | Real estate | 2011 |
| Ingmanthorpe RTM Company Limited | Households | 2023 |
| Innersense Aesthetics @ Wetherby Limited | Health & social care | 2016 |
| Innova Care Concepts Limited | Wholesale & retail | 2019 |
| Innova Property Consultants Limited | Professional & scientific | 2007 |
| Innovea Consulting Limited | Professional & scientific | 2024 |
| Innoventures (Commercial) Ltd | Real estate | 2025 |
| INS Network & Cloud Services Ltd | Information & communication | 2017 |
| Inspire Audio Visual (London) Ltd | Information & communication | 2015 |
| Inspire Audio Visual Ltd | Construction | 2012 |
| Inspired Change BIS Ltd | Professional & scientific | 2025 |
| Inspired Support Services Ltd | Health & social care | 2024 |
| Insta Phone Ltd | Wholesale & retail | 2020 |
| Instabus Ltd | Transport & logistics | 2023 |
| Instant Physio Ltd | Health & social care | 2015 |
| Integrian Limited | Information & communication | 1992 |
| Intelligent E Learning Ltd | Education | 2018 |
| INTERACT2 Limited | Professional & scientific | 2013 |
| Interactive Digital Systems Limited | Information & communication | 2013 |
| Interim Portfolio Management Limited | Professional & scientific | 2009 |
| International Care Delivery Alliance Limited | Other services | 2013 |
| Intertoy International Sales Limited | Administrative & support | 2016 |
| Intertoy Limited | Administrative & support | 1991 |
| Intro Supplies Limited | Wholesale & retail | 2023 |
| Invalesco Family Law Limited | Professional & scientific | 2018 |
| Ionisphere Provisioning Limited | Information & communication | 2024 |
| Ionyx Design Limited | Information & communication | 2019 |
| Ionyx Innovation Limited | Information & communication | 2015 |
| Ionyx Limited | Information & communication | 2019 |
| Iportalis Aggregation Limited | Information & communication | 2014 |
| Iportalis Limited | Administrative & support | 2016 |
| IR & DS Consultancy Services Ltd | Professional & scientific | 2015 |
| Islip Consulting Services Ltd | Professional & scientific | 2024 |
| Isokron Limited | Information & communication | 2015 |
| Italik Holdings Limited | Financial services | 2007 |
| Itchykoo Limited | Professional & scientific | 2010 |
| ITERO88 Ltd | Information & communication | 2023 |
| Iverenti Limited | Real estate | 2016 |
| IVY House Holidays Ltd | Hospitality | 2026 |
| IVY House PUB Co Ltd | Hospitality | 2025 |
| J & E Wray Investments Limited | Real estate | 2019 |
| J & K Burke Limited | Administrative & support | 2003 |
| J & L Hawkins Limited | Hospitality | 2011 |
| J & M 2024 Limited | Hospitality | 2024 |
| J & S PUB Company (Scalby) Ltd | Hospitality | 2019 |
| J C Trees Ltd | Agriculture & fishing | 2014 |
| J D Wallis Accountants Ltd | Professional & scientific | 2024 |