| JB Cranes Limited | Manufacturing | 2015 |
| JB Education (N.I.) Limited | Education | 2017 |
| JB Neurotech Ltd | Professional & scientific | 2024 |
| JBR Contract Solutions Ltd | Construction | 2017 |
| JC Developments (NI) Limited | Construction | 2013 |
| JC Property Solutions T/A One Lounge Hair & Beauty Limited | Other services | 2018 |
| Jcass Holdings Limited | Wholesale & retail | 2017 |
| JCF Cars & Recovery Ltd | Wholesale & retail | 2018 |
| JCM Autos Car Repairs Ltd | Wholesale & retail | 2026 |
| Jcnf Consulting Ltd | Information & communication | 2024 |
| JD Developments Ltd | Real estate | 2025 |
| JD NI Properties Ltd | Real estate | 2019 |
| JD Pickering Investments Ltd | Financial services | 2024 |
| JDC06 Ltd | Information & communication | 2019 |
| JDH Technical Limited | Professional & scientific | 2017 |
| Jdmce NI Limited | Wholesale & retail | 2025 |
| JDT Legal Ltd | Professional & scientific | 2024 |
| Jebron Genetics | Professional & scientific | 2026 |
| Jess Holdings (NI) Limited | Construction | 2023 |
| JET SET Events by Jenny Limited | Administrative & support | 2026 |
| JF Mechanical Ltd | Construction | 2025 |
| JF11 NI Ltd | Wholesale & retail | 2023 |
| JFS Cars Limited | Wholesale & retail | 2017 |
| JG Trade Sale Ltd | Wholesale & retail | 2024 |
| Jggp Ltd | Households | 2025 |
| JH Bearings Ltd | Wholesale & retail | 2024 |
| JHC Trans Ltd | Transport & logistics | 2026 |
| Jigsaw Project Management Solutions Ltd | Professional & scientific | 2012 |
| Jill Bennett Interiors Ltd | Professional & scientific | 2019 |
| JJ MC Joinery Ltd | Construction | 2026 |
| JJH Rope Access Services Limited | Construction | 2025 |
| JJR Products Ltd | Wholesale & retail | 2025 |
| Jlzdbc Ltd | Education | 2024 |
| JMA Systems Limited | Professional & scientific | 2019 |
| Jma-Ni Limited | Administrative & support | 2022 |
| JMB Bookkeeping & Accountancy Ltd | Professional & scientific | 2025 |
| JMC Hire Ltd | Administrative & support | 2014 |
| JMC Packaging Limited | Manufacturing | 2002 |
| JMF Catering Ltd | Hospitality | 2023 |
| JMK Teamwear Ltd | Wholesale & retail | 2024 |
| JMK Textiles Limited | Manufacturing | 2013 |
| JMQ Designs Ltd | Manufacturing | 2017 |
| JMV N.I. Ltd | Professional & scientific | 2024 |
| JOB Base Ltd | Administrative & support | 2025 |
| Jocs Electrical Ltd | Construction | 2024 |
| JOE Stinson Ltd | Agriculture & fishing | 2012 |
| Joe's Seafood Ltd | Hospitality | 2019 |
| John Cafferkey Plumbing & Heating Ltd | Construction | 2014 |
| John Diven & Co. Ltd | Wholesale & retail | 2019 |
| John Doone Haulage Contractor Limited | Transport & logistics | 2003 |
| John Eastwood & Sons Ltd | Extraterritorial | 1990 |
| John Hall & SON Ltd | Construction | 2022 |
| Johnathan Mcgeown Ltd | Construction | 2016 |
| Johnjo Contracts Limited | Construction | 2022 |
| Joloco Limited | Wholesale & retail | 2022 |
| Jones JR Sports Ltd | Education | 2024 |
| Jope Global Investments Ltd | Financial services | 2019 |
| Jordan Wilson Coaching Ltd | Other services | 2022 |
| Jottmur Ltd | Professional & scientific | 2022 |
| Joyce Clarke Estate Agents Ltd | Real estate | 2010 |
| Joyus Investments Limited | Professional & scientific | 2010 |
| JP O'Hagan Tyres Ltd | Wholesale & retail | 2013 |
| Jpjm Limited | Hospitality | 2018 |
| JPL Joinery Ltd | Construction | 2019 |
| Jrdmays Properties Ltd | Real estate | 2025 |
| Jrkl Properties Ltd | Real estate | 2012 |
| JRS NI Investments Limited | Construction | 2013 |
| JS Barry Limited | Wholesale & retail | 2015 |
| Judor Enterprises Ltd | Wholesale & retail | 2014 |
| Jugaroo Solutions Ltd | Professional & scientific | 2026 |
| Juice Belfast Limited | Information & communication | 2017 |
| Jurassic Wild Ltd | Arts & recreation | 2025 |
| Just a Chat Limited | Education | 2023 |
| Just N Case Ltd | Manufacturing | 2019 |
| Justjuice Ltd | Administrative & support | 2024 |
| JVD Trading Ltd | Wholesale & retail | 2025 |
| JW Gallery Ltd | Wholesale & retail | 2023 |
| JW1 Ltd | Construction | 2021 |
| K & E Trading Limited | Wholesale & retail | 2006 |
| K & S Haulage Ltd | Transport & logistics | 2018 |
| K Dixon Joinery Ltd | Construction | 2023 |
| K Haughey Painting Ltd | Construction | 2023 |
| K Jones Properties Ltd | Real estate | 2025 |
| K Mech Ltd | Manufacturing | 2023 |
| K Mulholland Ltd | Agriculture & fishing | 2012 |
| K P Coatings Ltd. | Construction | 2014 |
| K R Electrical Contracts Ltd | Construction | 2025 |
| K-Space (NI) Ltd | Manufacturing | 2006 |
| K-Space Holdings Ltd | Real estate | 2017 |
| K. Kebab Limited | Hospitality | 2017 |
| K.C.S Fire Safety Ltd | Professional & scientific | 2023 |
| K11 DZW Ltd | Hospitality | 2020 |
| K2 Sales Consulting Ltd | Professional & scientific | 2025 |
| K9 Detect Ltd | Administrative & support | 2025 |
| K9 Fertility Clinic (NI) Ltd | Administrative & support | 2020 |
| Kagroves Limited | Education | 2020 |
| Kailietech Ltd | Information & communication | 2026 |
| Kaizen Reliability Ltd. | Professional & scientific | 2024 |
| Kamell Limited | Real estate | 2006 |
| Kantuko Engineering Ltd | Manufacturing | 2024 |