| Inhouse-Ni Ltd | Information & communication | 2021 |
| Inn Choine Limited | Wholesale & retail | 2025 |
| Insight Clinic Ltd | Health & social care | 2022 |
| Inspired Greatness Ltd | Education | 2020 |
| Inspiring Yarns Academy Ltd | Education | 2024 |
| Inspiring Yarns CIC | Health & social care | 2021 |
| Integra Business Consultants Limited | Professional & scientific | 2010 |
| Interfurn Ltd | Real estate | 2000 |
| International Business Centre Ltd | Professional & scientific | 2019 |
| Intuitive Knowledge Ltd | Health & social care | 2018 |
| Inver Homes Limited | Construction | 2005 |
| Invisible Traffick NI | Other services | 2016 |
| Ionic Creative Design Ltd | Information & communication | 2021 |
| Iouyuan Ltd | Wholesale & retail | 2025 |
| Irish FLY Supplies Ltd | Wholesale & retail | 2024 |
| Irish Transport Heritage | Arts & recreation | 2020 |
| Irish Wheatgrass Juice Ltd | Mining & quarrying | 2012 |
| Ironbridge Consulting Group Ltd | Wholesale & retail | 2024 |
| Irvine & Sons Ltd | Real estate | 2025 |
| Irwin Avenue Management Company Ltd | Households | 2020 |
| Irwinwoods Ltd | Professional & scientific | 2010 |
| Isca Consulting Accountants Limited | Professional & scientific | 2015 |
| Isteip Limited | Information & communication | 2026 |
| ITS Payroll Limited | Administrative & support | 2019 |
| Ivan Mcknight Ltd | Wholesale & retail | 2025 |
| Ivory & Pearl Ltd | Wholesale & retail | 2013 |
| IVY Products Ltd | Wholesale & retail | 2020 |
| Iyas Qingchen Ltd | Wholesale & retail | 2024 |
| Izabelle Hammon (EU) Ltd | Extraterritorial | 2021 |
| J C Middleton Limited | Financial services | 2006 |
| J Clarke Marine Limited | Wholesale & retail | 2015 |
| J James N.I. Ltd | Construction | 2025 |
| J Mcdonald Florist Limited | Wholesale & retail | 2008 |
| J&J Leasing (NI) Ltd | Administrative & support | 2025 |
| J.A.M. Catering Ltd | Hospitality | 2019 |
| Jack MAC Consultancy Ltd | Professional & scientific | 2026 |
| Jacob Boyce Ltd | Transport & logistics | 2022 |
| Jacquelynann Creative Limited | Wholesale & retail | 2025 |
| Jacs Developments Limited | Construction | 2017 |
| JAD Commercial Ltd | Transport & logistics | 2021 |
| Jaenaticave Ltd | Wholesale & retail | 2025 |
| Jaerc Limited | Professional & scientific | 2022 |
| JAG Investment Holdings Limited | Financial services | 2022 |
| JAG Property Holdings Limited | Real estate | 2021 |
| James Colbert Limited | Manufacturing | 2019 |
| James Fulford & Co Ltd | Professional & scientific | 2012 |
| James H Hughes Limited | Construction | 2004 |
| James M Smyth Life & Pensions | | 1997 |
| James Osborne Limited | Wholesale & retail | 2019 |
| Jammy Expansion Ltd | Wholesale & retail | 2024 |
| Japanese Performance Car Services Ltd | Other services | 2018 |
| Jarosite Crest Limited | Wholesale & retail | 2025 |
| Jason Tiller Limited | Wholesale & retail | 2025 |
| Javatech Ltd | Manufacturing | 2023 |
| JAY Boys ED Ltd | Wholesale & retail | 2024 |
| Jayne Loughran Limited | Information & communication | 2024 |
| Jbtz Investments Limited | Construction | 2024 |
| JC Autohub Ltd | Wholesale & retail | 2026 |
| JC Equity (NI) T/A Black HAT Brickwork Ltd. | Construction | 2013 |
| JC FCV Ltd | Administrative & support | 2023 |
| JC Services & Maintenance Ltd | Water & waste | 2022 |
| JCE27 Ltd | Construction | 2026 |
| JCS Belfast Ltd | Professional & scientific | 2026 |
| JCS Repairs and Servicing Limited | Wholesale & retail | 2018 |
| JEM Swimming Limited | Arts & recreation | 2008 |
| Jemphrey Developments Limited | Construction | 2020 |
| Jesus Generation Church | Other services | 2014 |
| JET Peak Limited | Wholesale & retail | 2025 |
| Jevgenijsbeinarovicsde Limited | Wholesale & retail | 2024 |
| JHC Inc Limited | Financial services | 2022 |
| Jhesolutions Limited | Professional & scientific | 2015 |
| JI Cheng Trading Co Limited | Wholesale & retail | 2025 |
| Jiajie Trade Limited | Wholesale & retail | 2024 |
| Jiangquanqing Ltd | Wholesale & retail | 2025 |
| Jiangwenan Ltd | Wholesale & retail | 2025 |
| Jiapeng FHT Limited | Wholesale & retail | 2024 |
| Jiatao BAO Ltd | Wholesale & retail | 2024 |
| Jiawei Haque Ltd | Wholesale & retail | 2024 |
| Jieying Bay Ltd | Wholesale & retail | 2024 |
| Jinyuanbaoderetail Ltd | Wholesale & retail | 2025 |
| Jizhao Trade Limited | Wholesale & retail | 2023 |
| JJK Aero-Contracts Ltd | Professional & scientific | 2012 |
| JKK GmbH Ltd | Wholesale & retail | 2023 |
| JKN Property Ltd | Real estate | 2024 |
| Jktsoftware Ltd | Information & communication | 2016 |
| Jmec Properties Ltd | Real estate | 2025 |
| JO Leonard Plumbing and Heating Contractor Ltd | Construction | 2019 |
| Jofka Limited | Administrative & support | 2015 |
| John Andrews & Co. Limited | Real estate | 1909 |
| John Beers Ltd. | Wholesale & retail | 2014 |
| John Custom Ltd | Professional & scientific | 2023 |
| John Grant Limited | Real estate | 2006 |
| John Hagan Ltd | Manufacturing | 2007 |
| John Robb Interiors Ltd | Other services | 2011 |
| John Ross & SON Solicitors LLP | | 2014 |
| John Steele and SON Limited | Agriculture & fishing | 2025 |
| Johnston Webb Consultancy Ltd. | Information & communication | 2016 |
| Join Popular Ltd | Wholesale & retail | 2024 |
| Joincrin Limited | Wholesale & retail | 2025 |
| Jokata Limited | | 2000 |