| HS Bryans Ltd | Real estate | 2024 |
| HSB Associates Ltd | Professional & scientific | 2024 |
| Hsing 88 Ltd | Hospitality | 2024 |
| HUA Qing (Bangor) Limited | Hospitality | 2019 |
| Hudson Rose Developments Limited | Construction | 2017 |
| Hudson Rose Recruitment Ltd | Administrative & support | 2018 |
| Hugh Rooney ITS Limited | Information & communication | 2014 |
| Hughes & Associates Wealth Management CYF | Financial services | 2025 |
| Hullaballoo Limited | Wholesale & retail | 2025 |
| Hulse Davies Body Repairs Ltd | Wholesale & retail | 2020 |
| Hunter Developments Ltd | Hospitality | 2025 |
| Hunter Street Chester Limited | Construction | 2015 |
| Hutcheson Irvine Partnership LLP | | 2004 |
| Hutcheson Properties Ltd | Real estate | 1997 |
| HUW Saer CYF | Construction | 2017 |
| HWF Solutions Limited | Professional & scientific | 2023 |
| Hyfforddiant Menai Training Ltd | Education | 2024 |
| I L D Networks Limited | Manufacturing | 2001 |
| I R Property Management Ltd | Real estate | 2022 |
| I'M a Melter Ltd | Arts & recreation | 2024 |
| I-Mart Mobiles Bangor Ltd | Wholesale & retail | 2018 |
| I.M. & D.M. Owen (Adeiladwyr) CYF | Construction | 2008 |
| IAN Glasgow Car Sales Ltd | Wholesale & retail | 2016 |
| IAN Sturrock and Sons Ltd | Other services | 2022 |
| Iconic Blinds Ltd | Other services | 2025 |
| Iconic Seating (Europe) Limited | Wholesale & retail | 2026 |
| Idigital Accounting Ltd | Professional & scientific | 2026 |
| Igen Security Systems Ltd | Construction | 2017 |
| Igloo Survival Limited | Manufacturing | 2023 |
| Ikolo Limited | Professional & scientific | 2017 |
| Ikon Media Services Limited | Professional & scientific | 2015 |
| Illumerx Ltd | Professional & scientific | 2021 |
| Imadah Limited | Other services | 2019 |
| Image N.I Limited | Other services | 2014 |
| Imia Limited | Financial services | 2005 |
| Immanuel Church Millisle | Other services | 2022 |
| Impact People Consulting Ltd | Professional & scientific | 2023 |
| Impact Range Limited | Administrative & support | 2018 |
| IMT Nixon Consultancy Ltd | Professional & scientific | 2020 |
| IN the Name of COD Ltd | Hospitality | 2019 |
| IN Voice in Vision Limited | Information & communication | 2009 |
| In-Specification Ltd | Construction | 2021 |
| Incentive Digital Ltd | Wholesale & retail | 2012 |
| Inclusive Arts Ireland Ltd | Arts & recreation | 2026 |
| Independent Caravan Motorhome and Camping Club of Northern Ireland Limited-The | Arts & recreation | 2001 |
| Independent Energy Assessors Ltd | Construction | 2019 |
| Independent Finance Solutions Limited | Financial services | 2010 |
| India Street Glasgow Limited | Construction | 2020 |
| Indieprints Limited | Manufacturing | 2021 |
| Indigo (NI) Ltd | Wholesale & retail | 2010 |
| Infinity+ Health and Fitness Ltd | Arts & recreation | 2025 |
| Inflow Pilates Ltd | Arts & recreation | 2026 |
| INK & Aesthetics Ltd | Other services | 2022 |
| INK & Bundle Ltd | Manufacturing | 2025 |
| Innosec Limited | Information & communication | 2024 |
| Inspire Male Image Ltd | Other services | 2024 |
| Inspired Corporate Group Ltd | Financial services | 2020 |
| Instant OIL Limited | Wholesale & retail | 2022 |
| Instincta Limited | Information & communication | 2025 |
| Insula Wellbeing Ltd | Health & social care | 2022 |
| Integrated Power Control Solutions Ltd | Manufacturing | 2025 |
| Integrity Home Renovations Ltd | Construction | 2023 |
| Integrity Restaurant Group Ltd | Hospitality | 2023 |
| Intelligent Heating Supplies Limited | Wholesale & retail | 2011 |
| Interior Transition Limited | Construction | 2006 |
| International Mini Market OFF License Ltd | Wholesale & retail | 2023 |
| International Safety Components Limited | Manufacturing | 1994 |
| Intilaq Consulting Limited | Professional & scientific | 2025 |
| Into the White Space Ltd | Professional & scientific | 2025 |
| Iona Holdings Limited | Professional & scientific | 2008 |
| Iona Street Edinburgh Limited | Construction | 2017 |
| IP Lowry Ltd | Construction | 2017 |
| Ireland Refugee Board Limited | Administrative & support | 2025 |
| IRG Detailing & Valeting CYF | Other services | 2017 |
| Irwin Lewis Ltd | Real estate | 2022 |
| Ivory Technology Limited | Information & communication | 2023 |
| J & D Emerson Ltd | Real estate | 2025 |
| J & D Johnston Construction Ltd | Construction | 2025 |
| J & H Developments Ltd | Real estate | 1999 |
| J & T Building Contractors Ltd | Construction | 2018 |
| J Alwyn Roberts Plumbing & Heating CYF | Construction | 2010 |
| J and M Ferranti Technology Limited | Professional & scientific | 2015 |
| J Eccles Property Development Ltd | Real estate | 2025 |
| J H Plumbing and Renewables Ltd | Construction | 2025 |
| J I Foulkes MOT Centre Limited | Wholesale & retail | 2024 |
| J L S Car Sales Limited | Transport & logistics | 2004 |
| J L Scott Limited | Construction | 2018 |
| J&G Building and Assembling Ltd | Construction | 2026 |
| J&L Tree Contracting Ltd | Agriculture & fishing | 2023 |
| J-Bird Bakery Limited | Manufacturing | 2012 |
| J2K Fitness Ltd | Arts & recreation | 2013 |
| Jackay Limited | Construction | 2001 |
| Jade Software Engineering Ltd | Information & communication | 2025 |
| James Investment Properties Limited | Real estate | 2025 |
| Jamjar Catering Limited | Hospitality | 2023 |
| Jamuna (N.I.) Limited | Hospitality | 2024 |
| Jane Mannion Associates CYF. | Hospitality | 2019 |
| Japan Expert Ltd | Wholesale & retail | 2025 |
| JAR 26 Ltd | Information & communication | 2026 |
| Jask Property Ltd | Real estate | 2025 |