| Jill Jones Bridal Ltd | Wholesale & retail | 2020 |
| JJ Kirkpatrick Transport Ltd | Transport & logistics | 2026 |
| JLP Residential Ltd | Real estate | 2026 |
| JMB Properties Group Ltd | Real estate | 2025 |
| Jmzm Ltd | Other services | 2023 |
| JNK (N.I.) Limited | Construction | 2016 |
| Joan Holdings Ltd | Real estate | 2021 |
| John Rainey (Shipping & Consultancy) Limited | Administrative & support | 2018 |
| Johnny Whites Fish and Chip Shop Ltd | Hospitality | 2025 |
| Johnston Close Apartments Ltd | Real estate | 2004 |
| Jordan Products Ltd | Manufacturing | 2006 |
| Jordan Watts Haulage Ltd | Transport & logistics | 2020 |
| Jrtdesigns Limited | Wholesale & retail | 2022 |
| Jubilee Hall Land Management Ltd | Extraterritorial | 2015 |
| Jude Law Boutique Limited | Wholesale & retail | 2018 |
| Juju Properties Ltd | Real estate | 2023 |
| Just Mist Retail Ltd | Wholesale & retail | 2022 |
| JVA Group Limited | Wholesale & retail | 2020 |
| K2 Power Ltd | Energy | 2015 |
| Kane Farms Limited | Agriculture & fishing | 2017 |
| Karl Group Ltd | Real estate | 2015 |
| Karma Holywood Ltd | Other services | 2014 |
| Karmel Apostolic House | Other services | 2020 |
| KAT Computing Ltd | Information & communication | 2010 |
| KC Autos Limited | Wholesale & retail | 2022 |
| KDR Kitchens Ltd | Construction | 2021 |
| Keady Steam Bakery Limited | Manufacturing | 2019 |
| Kebabconi Ltd | Hospitality | 2025 |
| Keeble (N.I.) Limited | Manufacturing | 1988 |
| Keen on Simple Limited | Wholesale & retail | 2024 |
| Keltoi Ltd | Health & social care | 2025 |
| Kenny Developments Ltd | Construction | 2017 |
| Kentona Investments Limited | | 1993 |
| Keranbrae Management Co Ltd | Extraterritorial | 2003 |
| Kestrel Print and Supplies Limited | Manufacturing | 2019 |
| Key-Lite Lighting Services Ltd | Information & communication | 2022 |
| KG MGT Limited | Real estate | 2024 |
| Kilbride Sporthorses Ltd | Wholesale & retail | 2025 |
| Kilcoole Land Management Ltd | Households | 2021 |
| Kill IT With Quizzes Ltd | Information & communication | 2020 |
| Killaloe Apartments Ltd | Extraterritorial | 2002 |
| Killen ROW Management Co Ltd | Households | 2014 |
| Killen Studios Ltd | Information & communication | 2023 |
| Killimorrie Management Company Limited | Households | 2016 |
| Killuney Gardens Management Company Limited | Households | 2018 |
| Killuney Park Management Limited | Extraterritorial | 2009 |
| Killycavan Manor Land Management Ltd | Extraterritorial | 2002 |
| Killyfaddy Road Management Co Ltd | Households | 2018 |
| Killyglen Blackcave Management Limited | Households | 2006 |
| Kingsbridge Management Limited | Households | 1983 |
| Kingscourt Close Management Company Limited | Extraterritorial | 2004 |
| Kingsfort Mews Land Management Ltd | Households | 2026 |
| Kingsley Court Residents Limited | Households | 1990 |
| Kinvara Marketing Ltd | Professional & scientific | 2014 |
| Kitchens Direct (NI) Limited | Manufacturing | 2004 |
| Kithara Guitars Limited | Manufacturing | 2020 |
| Kleen Freaks Ltd | Manufacturing | 2011 |
| Kodatech Limited | Information & communication | 2018 |
| L G Hygiene Limited | Wholesale & retail | 2010 |
| LA Salle Court Management Company Limited | Households | 2008 |
| Lacolline Limited | Professional & scientific | 2019 |
| Ladore (NI) LLP | | 2011 |
| Laharna Management Company Limited | Extraterritorial | 2007 |
| Lakelands Land Management Ltd | Extraterritorial | 2001 |
| Lambfields Management Company Limited | Extraterritorial | 2002 |
| Lancia Developments Ltd | Construction | 2020 |
| Landlift Group Ltd | Real estate | 2026 |
| Landmark (Martin) Limited | Construction | 2019 |
| Landscaping Centre (Holdings) Limited | Other services | 2008 |
| Landscaping Centre Limited | Administrative & support | 1997 |
| Lapwing Productions Ltd | Information & communication | 2024 |
| Laughlin Lighting Limited | Construction | 2025 |
| Laurel Manor Management Company Limited | Households | 2017 |
| Laurel View Equestrian Centre Limited | Arts & recreation | 2012 |
| Lawnbrook Court Management Company Limited | Households | 2007 |
| Leinad Property Ltd | Real estate | 2012 |
| Leinad Retail Ltd | Wholesale & retail | 2014 |
| Leslie Stays Ltd | Real estate | 2020 |
| Let’S Expand Communication Ltd | Health & social care | 2019 |
| Lgjt Ltd | Information & communication | 2025 |
| Libleo Ltd | Professional & scientific | 2024 |
| Library Square Limited | Extraterritorial | 2005 |
| Libry Catering Limited | Hospitality | 2016 |
| Limefield Land Management Ltd | Extraterritorial | 2006 |
| Lindara Management Ltd | Extraterritorial | 2001 |
| Linen Fields Moira Management Company Limited | Households | 2017 |
| Linen Green Antrim Management Ltd | Extraterritorial | 2015 |
| Linnodee Limited | Professional & scientific | 1998 |
| Lismenary Motors Limited | Wholesale & retail | 2010 |
| Lismenary Road Management Co Ltd | Households | 2017 |
| Lisnalinchy Stables Ltd | Agriculture & fishing | 2021 |
| Lisnisky Management Company Limited | Extraterritorial | 2005 |
| Lisoneill Limited | Real estate | 2024 |
| Litore Promotions Ltd | Arts & recreation | 2020 |
| Little Blackthorn Property Ltd | Households | 2025 |
| Little Giant Productions Ltd | Arts & recreation | 2021 |
| Little Willow Productions Ltd | Arts & recreation | 2018 |
| Ljgni Ltd | Other services | 2022 |
| LLE Interior Design UK Ltd | Professional & scientific | 2019 |
| Lobaro Properties Ltd | Real estate | 2017 |