| Hurricane Media UK Limited | Information & communication | 2007 |
| Hurstone House Ltd | Hospitality | 2016 |
| Hutchins and Co Holdings Ltd | Financial services | 2021 |
| HW Testing Ltd | Information & communication | 2011 |
| Hwrb Limited | Real estate | 2020 |
| Hyas Associates Ltd | Professional & scientific | 2016 |
| Hyas Associates Trustees Ltd | Professional & scientific | 2024 |
| Hybrid Gym Limited | Arts & recreation | 2010 |
| Hybrid Property Holdings Ltd | Real estate | 2025 |
| Hyde Lane Management Company Limited | Households | 2004 |
| Hydo Ltd | Wholesale & retail | 2026 |
| Hydrotech Environmental & Civils Ltd | Water & waste | 2018 |
| Hylands View Equine Limited | Professional & scientific | 2017 |
| Hymr Ltd | Wholesale & retail | 2019 |
| Hypotenuse Health Limited | Health & social care | 2026 |
| Hythe Estates Ltd | Financial services | 2026 |
| I AM the Saint Ltd | Professional & scientific | 2023 |
| I J Assets Limited | Construction | 2023 |
| I Pro Hand Car Wash Limited | Administrative & support | 2023 |
| I&A Acoustics Limited | Professional & scientific | 2025 |
| I-One Post Limited | Information & communication | 2008 |
| IAN Airey Services Ltd | Professional & scientific | 2020 |
| IAN Hunt (Builders) Limited | Construction | 2003 |
| IAN Popham Racing Limited | Arts & recreation | 2019 |
| IAN Roper & Company Ltd | Professional & scientific | 2014 |
| Iaso Ltd | Financial services | 2026 |
| Ice Cold Hire Ltd | Administrative & support | 2025 |
| Ice Facilities Maintenance Limited | Professional & scientific | 2017 |
| Ice MAN Blasting Ltd | Administrative & support | 2024 |
| Icegold Limited | Construction | 2012 |
| ICL (South West) Limited | Wholesale & retail | 2021 |
| Icon Hairdressing Limited | Other services | 2008 |
| Icurtains Ltd | Extraterritorial | 2012 |
| Ideal Driver Training & Consultancy Ltd | Education | 2020 |
| Ideal Training Academy Limited | Education | 2018 |
| Idle Hands Studio LLP | | 2026 |
| Idmv Medical Limited | Health & social care | 2025 |
| IH & TU Ltd | Health & social care | 2017 |
| IHP Analytics Limited | Administrative & support | 2020 |
| IHP Holdings Limited | Financial services | 2021 |
| Ihres Limited | Financial services | 2020 |
| IJ Scaffolding Ltd | Construction | 2015 |
| IJC Property Developments Ltd | Real estate | 2025 |
| IJK Beauty Limited | Other services | 2023 |
| IJK Project Consulting Ltd | Construction | 2018 |
| IJK Properties Ltd | Real estate | 2019 |
| IJL Treasure Ltd | Wholesale & retail | 2017 |
| IK Indian Kitchen Ltd | Hospitality | 2025 |
| IKC Assets Limited | Financial services | 2018 |
| Ikmart Limited | Professional & scientific | 2015 |
| IL Basilico Ltd | Hospitality | 2022 |
| Ilchester Indian Limited | Hospitality | 2017 |
| Ilford Court Management (Taunton) Limited | Households | 1970 |
| Illumaphonium Ltd | Arts & recreation | 2018 |
| Illzfx Ltd | Administrative & support | 2024 |
| Ilminster Eyecare Ltd | Wholesale & retail | 2013 |
| IM a Hustler Baby Limited | Manufacturing | 2014 |
| IMB Data Ltd | Construction | 2013 |
| IMC Creations Limited | Professional & scientific | 2002 |
| Imex Ventures Limited | Information & communication | 2000 |
| Immortile Limited | Manufacturing | 2004 |
| Impact Design & Advertising Limited | Professional & scientific | 1987 |
| Impact Design & Marketing Limited | Professional & scientific | 1996 |
| Impak Ltd | Professional & scientific | 2023 |
| Impala Property Limited | Real estate | 2021 |
| Impellr Limited | Extraterritorial | 2024 |
| Imperial Chemists Limited | Wholesale & retail | 2023 |
| IMS Mechanical & Electrical Limited | Construction | 2011 |
| IN House Training & Consultancy Limited | Professional & scientific | 2015 |
| IN the MIX Youth Project | Education | 2011 |
| Inatuni Ltd | Information & communication | 2024 |
| Incamera Studios Ltd | Information & communication | 2012 |
| Incrediclean Ltd | Administrative & support | 2024 |
| Incyte Education Ltd | Professional & scientific | 2005 |
| Incyte International Ltd | Extraterritorial | 2010 |
| Incyte Ltd | Extraterritorial | 2007 |
| Independent Anatomic Pathology Ltd | Professional & scientific | 2021 |
| Independent Asbestos Training Providers Limited | Other services | 2010 |
| Indio Fields (Bovey Tracey) Management Company Limited | Households | 2023 |
| Indus Fusion Ltd | Information & communication | 2018 |
| Ines Ltd | Financial services | 2025 |
| Infinite Players Ltd | Information & communication | 2018 |
| Infinity Quality Management Solutions Ltd | Professional & scientific | 2023 |
| Infocus Property Ltd | Real estate | 2020 |
| Ingenious Move Ltd | Transport & logistics | 2020 |
| Inklings Tattoo Limited | Arts & recreation | 2022 |
| Innatus Digital Ltd | Professional & scientific | 2020 |
| Inner Calm Birthing Ltd | Health & social care | 2026 |
| Innovate Developments Limited | Construction | 2006 |
| INO8 UK Limited | Information & communication | 2024 |
| Inobld Limited | Construction | 2022 |
| Inplay Golf Limited | Arts & recreation | 2013 |
| Insight PDM (Group) Ltd | Financial services | 2024 |
| Insight PDM Limited | Real estate | 2011 |
| Inspiration Brands Group Limited | Financial services | 2018 |
| Inspire Hockey Limited | Education | 2015 |
| Inspired Collective Ltd | Professional & scientific | 2019 |
| Inspired Partnership Limited | Professional & scientific | 2011 |
| Inspired Planet Limited | Other services | 2021 |
| Instinct Boxing and Fitness Limited | Education | 2022 |