| Imfe Ltd | Professional & scientific | 2020 |
| Immobilier France Ltd | Health & social care | 2005 |
| IMP Services Ltd | Professional & scientific | 2021 |
| Impact QS Support Limited | Professional & scientific | 2020 |
| Imperial Pet Taxis Ltd | Transport & logistics | 2026 |
| Implode Publishing Limited | Information & communication | 2015 |
| Importec Ltd | Wholesale & retail | 2014 |
| IN Expectation | Administrative & support | 2021 |
| IN the Pines Media Ltd | Information & communication | 2007 |
| IN the Sticks Childcare Ltd | Health & social care | 2024 |
| Inades Foods Limited | Wholesale & retail | 2025 |
| Inades Services Ltd | Administrative & support | 2026 |
| Inch Worm Productions Limited | Arts & recreation | 2011 |
| Inclusive Systems Accessible Solutions (Isas) Limited | Information & communication | 2026 |
| Independence First Limited | Health & social care | 2019 |
| Independent SW Services Ltd | Health & social care | 2021 |
| Indigo Alpha Tech Ltd | Wholesale & retail | 2012 |
| Infini Talent Ltd | Professional & scientific | 2022 |
| Info Booster Ltd | Information & communication | 2014 |
| Infosmart Ltd | Professional & scientific | 2005 |
| Ingles Manor Apartments Management Limited | Households | 2019 |
| Ingles Manor Management Limited | Households | 2019 |
| Ingles Mews Management Limited | Households | 1992 |
| Ingles Road Management Company Limited | Extraterritorial | 2012 |
| Inkd by IS Ltd | Arts & recreation | 2026 |
| Inn Doors Limited | Hospitality | 2015 |
| Innosol Limited | Information & communication | 2010 |
| Innova Events Management Ltd | Administrative & support | 2021 |
| Innovation Flooring UK Ltd | Construction | 2015 |
| Innovative Recruitment Limited | Administrative & support | 2022 |
| Innovativegrid Limited | Information & communication | 2024 |
| Inochi Defence Media Ltd | Professional & scientific | 2019 |
| Inoox Ltd | Information & communication | 2020 |
| Inscope Testing Limited | Information & communication | 2008 |
| Insight Training, Consultancy and Development Limited | Professional & scientific | 2026 |
| Inspired to Build Ltd | Construction | 2013 |
| Insurelead Ltd | Information & communication | 2024 |
| International Event Energy Transition Ltd | Professional & scientific | 2019 |
| International Finance Concept Limited | Real estate | 2020 |
| Interns Online Limited | Administrative & support | 2021 |
| Intrepid Endeavours Ltd | Information & communication | 2025 |
| Invectis Limited | Real estate | 2021 |
| Inventome Limited | Information & communication | 2006 |
| Invest in Autographs Limited | Professional & scientific | 2009 |
| Investinmind Ltd | Professional & scientific | 2019 |
| Invicta Heating Specialists Limited | Construction | 2023 |
| Invicta Road 1971 Limited | Extraterritorial | 2014 |
| Invictafx Ltd | Arts & recreation | 2026 |
| Invictus Plumbing Services Limited | Construction | 2022 |
| Inviso Limited | Information & communication | 2004 |
| IO Business Solutions Limited | Information & communication | 2007 |
| Iprog Limited | Information & communication | 2007 |
| IR Studios Limited | Professional & scientific | 2018 |
| Ireland Court (Ashford) Management Ltd | Households | 2005 |
| Ireland Court Management Company Limited | Households | 1990 |
| Irmak Caffe Ltd | Hospitality | 2025 |
| IRT Fitness Limited | Health & social care | 2026 |
| Ishmo Ltd | Education | 2026 |
| Islams and Sons Ltd | Real estate | 2024 |
| Issy Oakes Photography Limited | Professional & scientific | 2015 |
| Istheresomebody Ltd | Information & communication | 2024 |
| ISU Studio Limited | Information & communication | 2021 |
| IT Tech Services & Consultation Ltd | Information & communication | 2024 |
| It's Danny Windsor Ltd | Professional & scientific | 2023 |
| Itps (Europe) Ltd | Education | 2012 |
| Ittb Ltd | Administrative & support | 2015 |
| IVV International Limited | Information & communication | 2016 |
| IW Kitchens Ltd | Construction | 2024 |
| Izele Community Interest Company | Information & communication | 2016 |
| J & I Motors Ltd | Wholesale & retail | 2025 |
| J & K Holdings London Limited | Real estate | 2016 |
| J & K Kleen Ltd | Administrative & support | 2008 |
| J Boswell Properties Limited | Real estate | 2025 |
| J Collectionuk Ltd | Wholesale & retail | 2024 |
| J D and C Ltd | Manufacturing | 2024 |
| J Gannon Crushing & Recycled Materials Ltd | Water & waste | 2008 |
| J Gould Limited | Construction | 2015 |
| J Ireland Ltd | Construction | 2017 |
| J N Carpentry and Renovations Ltd | Construction | 2026 |
| J Nails 123 Ltd | Other services | 2024 |
| J Smith Drylining Ltd | Construction | 2019 |
| J&K Holdings International Limited | Real estate | 2020 |
| J.A. Gulland Limited | Health & social care | 2015 |
| J.E.B Welding Ltd | Manufacturing | 2019 |
| Jabtek Limited | Manufacturing | 2008 |
| Jacaranda Fitness Ltd | Other services | 2025 |
| Jack Godden Agri Ltd | Agriculture & fishing | 2023 |
| JAG Engineering Designs Ltd | Construction | 2010 |
| Jakefrailway Limited | Professional & scientific | 2025 |
| Jaklai Engineering and Construct Ltd | Professional & scientific | 2019 |
| Jalex Catering Limited | Hospitality | 2020 |
| James Robertson Consulting Ltd | Professional & scientific | 2023 |
| Jamie Muir Films Ltd. | Information & communication | 2018 |
| Janus Developments Limited | Real estate | 1988 |
| Jarvis Langmead Limited | Extraterritorial | 2026 |
| Jasm Travels Limited | Administrative & support | 2025 |
| Jazmin Beach Ltd | Real estate | 2012 |
| JB Bespoke Interiors Ltd | Construction | 2025 |
| JB Business Consultants Ltd | Hospitality | 2024 |
| Jb's Pet Sitting and More Ltd | Other services | 2022 |