| Iavird Nschad Ltd | Wholesale & retail | 2024 |
| Iazero Ltd | Professional & scientific | 2023 |
| IBE Ltd | Construction | 2020 |
| Ibex Plus Partners Limited | Hospitality | 2022 |
| Ibhawoehi Ltd | Health & social care | 2023 |
| Ibip Holding Limited | Energy | 2017 |
| Ibiza Sunbeds Ltd | Other services | 2023 |
| IBLYALTRADING71 Limited | Wholesale & retail | 2025 |
| IBU Property Limited | Real estate | 2024 |
| Ibuildni Ltd | Construction | 2025 |
| IC Books Ltd | Professional & scientific | 2020 |
| IC Studios Entertainment Limited | Information & communication | 2025 |
| Icanmum & Icandad Ltd | Information & communication | 2026 |
| Ice Cream Productions Limited | Information & communication | 2012 |
| Iceblast NI Ltd | Manufacturing | 2021 |
| Icecube Shot Limited | Wholesale & retail | 2025 |
| Icesmok.Com Ltd | Wholesale & retail | 2023 |
| Iclean Homestore PTE. Ltd | Wholesale & retail | 2025 |
| Icmo Ltd | Manufacturing | 2021 |
| Icon Construction Management Ltd | Construction | 2010 |
| Icon Management Company (Northern Ireland) Limited | Households | 2008 |
| Iconic Protech Ltd | Wholesale & retail | 2023 |
| Iconicrf Limited | Professional & scientific | 2017 |
| Iconiq Sports Limited | Wholesale & retail | 2024 |
| ICP UK & IRE Ltd | Construction | 2022 |
| Icts Services Ltd | Wholesale & retail | 2018 |
| IDC Consultancy Limited | Information & communication | 2014 |
| Idea Mint Ltd | Administrative & support | 2021 |
| Ideagene Limited | Information & communication | 2013 |
| Ideal Future Trade Ltd | Wholesale & retail | 2024 |
| Ideal Seaview Developments LLP | | 2021 |
| Identity Exploration (Holdings) Ltd | Financial services | 2014 |
| Idonate UK Ltd | Other services | 2024 |
| Idyll Restaurants Limited | Hospitality | 2023 |
| IFA Stadium Development Company Limited | Arts & recreation | 2011 |
| IFC Media Limited | Information & communication | 2012 |
| IFJ Services UK Ltd | Construction | 2015 |
| Ifni - Debt LP | | 2023 |
| Ifni - Equity LP | | 2023 |
| Ifourcs (N.I.) Limited | Professional & scientific | 2019 |
| IFQ Limited | Education | 2022 |
| Ifrs Accounting Limited | Financial services | 2008 |
| Ifsh Ltd | Real estate | 2018 |
| Igame Media Limited | Administrative & support | 2014 |
| Igloo Pizza Co. Limited | Hospitality | 2023 |
| Ignite (Ireland) Ltd | Extraterritorial | 2013 |
| Ignite Accelerator NI Limited | Other services | 2022 |
| Ignite Coaching Ltd | Professional & scientific | 2021 |
| Ignite Empire Ltd | Professional & scientific | 2024 |
| Ignite Plumbing Services Ltd Ltd | Wholesale & retail | 2015 |
| Ignitus Advisory Services Limited | Professional & scientific | 2025 |
| Iguard Global Limited | Manufacturing | 2025 |
| IH Pro Ltd | Wholesale & retail | 2025 |
| IK Consulting Limited | Professional & scientific | 2007 |
| IK Traders Ireland Limited | Hospitality | 2021 |
| Ikigaieco Ltd | Wholesale & retail | 2024 |
| Ikleen UK Limited | Administrative & support | 2025 |
| ILC Healthcare Ltd | Administrative & support | 2025 |
| Ilcu Savings Protection Company Limited-The | | 1989 |
| Ilelawa Ltd | Wholesale & retail | 2025 |
| Iliv Apartments (UK) Limited | Real estate | 2021 |
| ILL Records Ltd | Information & communication | 2018 |
| Illimitato Limited | Administrative & support | 2016 |
| Illuminate Analytics Ltd | Information & communication | 2021 |
| Illumination Health Ltd | Health & social care | 2023 |
| Ilmtrix AI Limited | Information & communication | 2025 |
| ILP Traderz Ltd | Wholesale & retail | 2023 |
| Ilumine Technology Limited | Wholesale & retail | 2025 |
| Im-Ex Trade Ltd | Hospitality | 2023 |
| Image Automotive Holdings N.I Ltd | Wholesale & retail | 2021 |
| Image Musical Theatre (UK) Limited | Administrative & support | 2013 |
| Image ZOO Limited | Professional & scientific | 2004 |
| Imagine Belfast Ltd | Arts & recreation | 2012 |
| Imagine Marquees Limited | Arts & recreation | 2020 |
| Imanltd Limited | Hospitality | 2025 |
| Imax Ltd | Real estate | 2016 |
| Imen's Ltd | Hospitality | 2017 |
| IMG Developments Ltd | Real estate | 2013 |
| Imhotep Diagnostics & Therapeutics Limited | Health & social care | 2012 |
| IMI Executive Development (N.I) Limited | Professional & scientific | 1997 |
| IML Hygiene Services Ltd | Administrative & support | 2014 |
| IMM Consulting Ltd | Professional & scientific | 2018 |
| IMM Exhibition and Event Management Services Ltd | Professional & scientific | 2023 |
| Immense Space Network Ltd | Information & communication | 2026 |
| Immerse Academy CIC | Education | 2026 |
| Immerse Studios Ltd | Education | 2026 |
| Immrsv Investments Limited | Professional & scientific | 2017 |
| Imoo Store Limited | Wholesale & retail | 2025 |
| IMP Distribution Limited | Other services | 2022 |
| Impact (NI) Ltd | Administrative & support | 2012 |
| Impact Bathroom Designs Limited | Extraterritorial | 2010 |
| Impact Economics Limited | Professional & scientific | 2025 |
| Impact Signs Belfast Limited | Professional & scientific | 2014 |
| Imperial PMC Ltd | Hospitality | 2026 |
| Imperial Recruitment and Staffing Solutions Limited | Administrative & support | 2022 |
| Imperial Tobacco Trading Limited | | 1983 |
| Impexline L.P. | | 2018 |
| Imphc Ltd | Real estate | 2022 |
| Imphora Limited | Information & communication | 2001 |
| Import Export Vehicles Ltd | Transport & logistics | 2026 |