| I T Lancaster Limited | Financial services | 2012 |
| IAN Skelton Limited | Construction | 2016 |
| IB Plumbing LLP | | 2021 |
| Ibuy and Sell Limited | Wholesale & retail | 2014 |
| Ibuy and Sell Southwest Limited | Wholesale & retail | 2015 |
| Icen Limited | Other services | 2008 |
| Icen Meadows Ltd | Real estate | 2025 |
| Ideas Engineering Consultancy Limited | Professional & scientific | 2021 |
| IDL Building Maintenance Ltd | Construction | 2026 |
| IF I Go Down to the Woods Today Limited | Information & communication | 2025 |
| Igaming Analytics Strategy and Marketing Limited | Professional & scientific | 2014 |
| Imagine Cosy Ltd | Wholesale & retail | 2025 |
| Imobb Ltd | Information & communication | 2013 |
| Impact Signs and Print Limited | Manufacturing | 2007 |
| IN the BAG PR Ltd | Professional & scientific | 2015 |
| IN the Box Dorset Ltd | Wholesale & retail | 2021 |
| Inchenergy Limited | Professional & scientific | 2025 |
| Index Marine Limited | Administrative & support | 2015 |
| Industria Consultancy Ltd | Professional & scientific | 2020 |
| Inferno Performance Limited | Wholesale & retail | 2026 |
| Influx Mobile Limited | Professional & scientific | 2009 |
| INITIAL1 Ltd | Professional & scientific | 2008 |
| Inked Engine Ltd | Administrative & support | 2014 |
| Innotec Manufacturing Limited | Administrative & support | 2002 |
| Inpac Automation Limited | Administrative & support | 2006 |
| Inside N OUT (UK) Limited | Construction | 2009 |
| INSIGHT2INCOME Limited | Professional & scientific | 2017 |
| Instergas Boiler Care Limited | Construction | 2021 |
| Intavida Ltd | Wholesale & retail | 2026 |
| Integrity Engineering Limited | Professional & scientific | 2022 |
| Intelligent Cleaning Ltd | Administrative & support | 2009 |
| Intergrated Security Consultants Ltd | Administrative & support | 2026 |
| International Optimist Class Association (UK) Limited | Arts & recreation | 2015 |
| International Theming Limited | Arts & recreation | 2013 |
| Internet Mentor Limited | Information & communication | 2011 |
| Intl Coaching Company Ltd | Administrative & support | 2026 |
| Invenio Motus Limited | Information & communication | 2025 |
| Involve Care Solutions Limited | Health & social care | 2023 |
| Iphoneography Central Ltd | Information & communication | 2018 |
| Ipress Studio Ltd | Information & communication | 2013 |
| Iris INT Ltd | Real estate | 2009 |
| ISI (Weymouth) Limited | Hospitality | 2013 |
| Isle Properties (Southern) Limited | Real estate | 2000 |
| Issey Socials Ltd | Professional & scientific | 2024 |
| IST Diving Ltd | Transport & logistics | 2015 |
| Itps Renewables Energy Ltd | Energy | 2008 |
| Itsa Design Limited | Professional & scientific | 2021 |
| Itsa Group Ltd | Professional & scientific | 2018 |
| Itsa House Ltd | Real estate | 2020 |
| Itsa Service Limited | Professional & scientific | 2026 |
| Itsa Studio Limited | Manufacturing | 2021 |
| Itsa Style Limited | Other services | 2021 |
| Itsa Trade Limited | Professional & scientific | 2026 |
| J & a Property Rentals Ltd | Hospitality | 2014 |
| J & B Precision Engineering Ltd | Manufacturing | 2003 |
| J C Cleaning Services Ltd | Administrative & support | 2009 |
| J D H Consultants (UK) Limited | Public administration | 2008 |
| J E Mcdermott Ltd | Other services | 2016 |
| J Flann General Builders Ltd | Construction | 2014 |
| J G Taylor Property Ltd | Real estate | 2026 |
| J H B Carpentry Ltd | Manufacturing | 2010 |
| J H Edwards Limited | Information & communication | 1993 |
| J H Taverns Limited | Hospitality | 2009 |
| J J Electrical Holdings Limited | Real estate | 2020 |
| J L S M Limited | Information & communication | 2005 |
| J Morrison Property Ltd | Real estate | 2024 |
| J R Autotechnics Limited | Wholesale & retail | 2012 |
| J T Investments (Dorset) Limited | Construction | 2014 |
| J&F Holdings (SW) Limited | Financial services | 2019 |
| J.C. & F.F. Dovey & Sons Ltd | Agriculture & fishing | 2002 |
| J.J. Electrical Limited | Construction | 2002 |
| J.M Tree and Garden Services Limited | Administrative & support | 2022 |
| J.R. Spiller Limited | Real estate | 1957 |
| J7PLAY Ltd | Wholesale & retail | 2019 |
| Jacobs Estates and Rental LLP | | 2011 |
| Jacobs Partnership LLP | | 2008 |
| Jade Seabits Ltd | Hospitality | 2024 |
| Jaic Limited | Manufacturing | 2003 |
| James Armitage Limited | Professional & scientific | 2007 |
| James Haggett Property Investments Ltd | Real estate | 2024 |
| James O'Brien Hair Limited | Other services | 2014 |
| James Young Associates Limited | Financial services | 2009 |
| Jamesia Blooms and Occasions Ltd | Wholesale & retail | 2025 |
| Jamesthethatcher Ltd | Construction | 2024 |
| Jasmine 121 Limited | Hospitality | 2021 |
| Jason Taylor Window Cleaning Limited | Administrative & support | 2007 |
| JAY PSO Solutions Ltd | Information & communication | 2013 |
| Jays Entertainments Limited | Arts & recreation | 2014 |
| JBA Asset Management Limited | Households | 2026 |
| JBF Welding & Fabrication Limited | Professional & scientific | 2017 |
| Jbpl Investments Ltd | Real estate | 2026 |
| Jcactivities Limited | Arts & recreation | 2013 |
| JCH Tech Ltd | Professional & scientific | 2022 |
| JCS WEY Limited | Construction | 2023 |
| JD Talent Management Limited | Administrative & support | 2024 |
| Jdaver Ltd | Education | 2023 |
| Jdcg IP Limited | Professional & scientific | 2019 |
| JDG Dorset Limited | Hospitality | 2025 |
| Jdhl Ltd | Real estate | 2017 |
| Jeans Shop Ltd | Wholesale & retail | 2006 |