| Insuppa Ltd | Wholesale & retail | 2021 |
| Insurvey Limited | Professional & scientific | 2008 |
| Integrated Document Solutions Limited | Information & communication | 1997 |
| Integrated Pathology Partnerships Limited | Health & social care | 2010 |
| Integrious Ltd | Information & communication | 2011 |
| Intelligent Code Ltd | Information & communication | 2020 |
| Intelligent Enterprise Products Ltd | Information & communication | 2011 |
| Intelligent Motorist Ltd | Wholesale & retail | 2019 |
| Intelligent Residential Ltd | Real estate | 2026 |
| Interbru Limited | Wholesale & retail | 2014 |
| International Environment Sustainability Group Limited | Professional & scientific | 2017 |
| Inthatch Ltd | Wholesale & retail | 2012 |
| Intracare Investments Limited | Administrative & support | 2012 |
| Introtweet Franchise Ltd | Professional & scientific | 2022 |
| Introtweet Ltd | Professional & scientific | 2018 |
| Invictus Executive Search LLP | | 2009 |
| Ionel's Marine & Mechanical Ltd | Manufacturing | 2024 |
| Ionizingenergy Limited | Water & waste | 2013 |
| IP Contract Services Ltd | Construction | 2018 |
| IPAINT4U Ltd | Construction | 2014 |
| IPL Holdings Ltd | Financial services | 2023 |
| IPN One Limited | Information & communication | 2011 |
| IQX2 Limited | Professional & scientific | 2011 |
| Irie 7 Ltd | Hospitality | 2019 |
| Iris Galerie London Ltd | Wholesale & retail | 2022 |
| Irnham Mews (Minehead) Management Company Limited | Households | 2000 |
| Iron Bear Clothing Ltd | Wholesale & retail | 2025 |
| Ironstone Ventures Limited | Financial services | 2000 |
| Irritech Holdings Limited | Financial services | 2015 |
| Irritech Limited | Professional & scientific | 2002 |
| Irving Scott Limited | Administrative & support | 2013 |
| Isakina Limited | Health & social care | 2021 |
| Isca Estates Holding Ltd | Financial services | 2024 |
| Isca Estates Ltd | Real estate | 2024 |
| Isca Oncology Ltd | Health & social care | 2017 |
| ISK Software Ltd | Information & communication | 2019 |
| Iskia Boutique Limited | Wholesale & retail | 2021 |
| Isle Fruits (Somerset) Limited | Agriculture & fishing | 2023 |
| Isle Fruits Limited | Agriculture & fishing | 2023 |
| Isles of Scilly Medical Services Limited | Health & social care | 2013 |
| ISM Fantasy Games Limited | Arts & recreation | 2002 |
| IT Starts With ME Ltd | Information & communication | 2025 |
| Itoa Admin Ltd | Professional & scientific | 2018 |
| IVY House of Wellness Limited | Other services | 2025 |
| Ivycrest Limited | Wholesale & retail | 1991 |
| Ivymax 2 Ltd | Hospitality | 2022 |
| Ivymax Ltd | Hospitality | 2020 |
| J Consultants Ltd | Transport & logistics | 2023 |
| J & a Consultants Limited | Professional & scientific | 1995 |
| J & a Davies Holdings Limited | Financial services | 2018 |
| J & E Meckiff Property Limited | Real estate | 2021 |
| J & H Parsons Limited | Real estate | 1982 |
| J & J Catering Services Ltd | Hospitality | 2019 |
| J & J Johns Ltd | Health & social care | 2024 |
| J & M Cowling Ltd | Real estate | 2024 |
| J & M Cowling Property Limited | Real estate | 2026 |
| J & R Nails Taunton Ltd | Other services | 2023 |
| J & S Webster Limited | Real estate | 2018 |
| J and J Homes Private Ltd | Real estate | 2025 |
| J and M Property Services SW Ltd | Real estate | 2019 |
| J Bartlett Carpentry Limited | Construction | 2019 |
| J Bedward Builders Ltd | Construction | 2024 |
| J C Plumbing & Heating Supplies Limited | Wholesale & retail | 2016 |
| J Coulston (Momus Safety) Ltd | Health & social care | 2019 |
| J D Lacey Damp Proofing Ltd | Construction | 2025 |
| J D Rossiter Ltd | Health & social care | 2014 |
| J Freeman Contractors Ltd | Agriculture & fishing | 2016 |
| J G D Construction Limited | Construction | 2007 |
| J Gliddon & Sons Limited | Wholesale & retail | 1954 |
| J H Total Construction Limited | Construction | 2022 |
| J Hemingway Ltd | Financial services | 2021 |
| J J Automotive Ltd | Wholesale & retail | 2025 |
| J Lang Consulting Limited | Professional & scientific | 2024 |
| J P Bage Building Services Limited | Construction | 2017 |
| J R Auto Works Ltd | Wholesale & retail | 2020 |
| J R Gliddon Law Limited | Professional & scientific | 2017 |
| J S Morris Groundworks Limited | Construction | 2006 |
| J Stone Electrical Ltd | Construction | 2007 |
| J Stone Electrical Renewables Ltd | Construction | 2023 |
| J Symes & SON Limited | Construction | 2006 |
| J Symes Painting Contractor Ltd | Construction | 2006 |
| J T J Limited | Wholesale & retail | 1992 |
| J V Farming Limited | Agriculture & fishing | 2002 |
| J W Cooper (South West) Limited | Information & communication | 2016 |
| J Whitfield Ltd | Professional & scientific | 2024 |
| J&B Edwards Holdings Ltd | Health & social care | 2023 |
| J&B Edwards Ltd | Health & social care | 2023 |
| J&J Culmstock Ltd | Real estate | 2017 |
| J&S Haygrove Medical Limited | Health & social care | 2026 |
| J, S and J Down Limited | Agriculture & fishing | 2015 |
| J. & B. Gibbs & Sons Limited | Real estate | 1980 |
| J. a. Rowley Limited | Other services | 2018 |
| J. Bland Construction Ltd | Construction | 2026 |
| J. Bulcock Consultancy Limited | Professional & scientific | 2003 |
| J. Compton Consulting Limited | Information & communication | 2007 |
| J. Neal Artisan Builders Limited | Construction | 2014 |
| J. R Jackson Limited | Construction | 2024 |
| J. Viveash Limited | Real estate | 1977 |
| J.A.L. Restorations Limited | Professional & scientific | 2010 |
| J.B.Atlas Ltd | Wholesale & retail | 2021 |