| Kaseal Ltd | Administrative & support | 2021 |
| KC Food Solutions Ltd | Professional & scientific | 2024 |
| KCB Group Ltd | Other services | 2016 |
| KD Kars Ltd | Wholesale & retail | 2013 |
| Kdmautomation Ltd | Wholesale & retail | 2025 |
| Keady ROW Ltd | Professional & scientific | 2019 |
| Keego Investments Ltd | Construction | 2020 |
| Keelmount Grange Management Ltd | Administrative & support | 2003 |
| Keith Anderson Driving Limited | Transport & logistics | 2025 |
| Keith Hamilton Ltd | Financial services | 2021 |
| Kelly Enterprises (N.I.) Ltd | Wholesale & retail | 2017 |
| Kelly Groundwork & Contracts Ltd | Administrative & support | 2026 |
| Kelly Studio Architects Ltd | Professional & scientific | 2024 |
| Kemark Limited | Construction | 1998 |
| Kennedy Contract Services Ltd | Construction | 2023 |
| Kenneth Dougan (Tyres) Ltd | Wholesale & retail | 1987 |
| Keonan Stables Limited | Agriculture & fishing | 2010 |
| Keppa Electrical Limited | Construction | 2025 |
| Kernan Flying School Ltd | Education | 2021 |
| Kernan Valley Flying Club Ltd | Arts & recreation | 2022 |
| Kerrcraft Limited | Construction | 2023 |
| Kestrel FM Ltd | Construction | 2026 |
| Key Analysis Ltd | Financial services | 2017 |
| Khlm Limited | Real estate | 2012 |
| KHO Farrell Ltd | Hospitality | 2019 |
| Killaney Developments Limited | Construction | 2005 |
| Killymeal Grange Management Company Limited | Real estate | 2014 |
| Kilmagamish Holsteins Limited | Agriculture & fishing | 2025 |
| Kilmore Contracts Limited | Construction | 2010 |
| Kilmore Freight Limited | Transport & logistics | 2011 |
| Kilmore Group Ltd | Financial services | 2025 |
| Kilmore Holdings Ltd | Financial services | 2024 |
| Kilmore Investments Limited | Real estate | 1990 |
| Kilmore Manor Management Limited | Hospitality | 2002 |
| Kilmore Oneilland BPT Ltd | Real estate | 2021 |
| Kilmore Services & Grocery Ltd | Wholesale & retail | 2018 |
| Kilmore Stafford Ltd | Professional & scientific | 2022 |
| Kilmore Storage & Distribution Ltd | Transport & logistics | 2017 |
| Kiln Contracts Ltd | Construction | 2026 |
| Kiln Management Banbridge Limited | Households | 2016 |
| Kilvergan Properties Limited | Real estate | 2006 |
| Kinetic Medical (NI) Limited | Health & social care | 2020 |
| Kingsroad Properties Limited | Real estate | 2025 |
| Kingstonford Developments Ltd | Real estate | 2021 |
| Kinkaid Living Ltd | Real estate | 2025 |
| Kinkaid Residential Ltd | Construction | 2014 |
| Kintec Solutions NI Ltd | Information & communication | 2025 |
| KKJ Consultancy Ltd | Other services | 2016 |
| Kleeny NI Limited | Administrative & support | 2024 |
| Klink Fitness Ltd | Manufacturing | 2020 |
| KM Photography Limited | Professional & scientific | 2018 |
| Kmcrm Ltd | Other services | 2022 |
| KMG Road Services Ltd | Construction | 2015 |
| Knead to Know Ltd | Manufacturing | 2026 |
| Knitted Knockers of NI Ltd | Health & social care | 2021 |
| KP2K Enterprises Ltd | Wholesale & retail | 2025 |
| Kpod Property Limited | Households | 2024 |
| KPS Limited | Real estate | 2006 |
| Krish Property Services Limited | Real estate | 2023 |
| KT Contracts Ltd | Construction | 2026 |
| Kurdish Family Ltd | Other services | 2025 |
| Kyber Digital Ltd | Administrative & support | 2001 |
| Kynora Limited | Wholesale & retail | 2025 |
| L & B (NO 59) Limited | Extraterritorial | 2004 |
| L & P Retail Limited | Wholesale & retail | 2012 |
| L D Agri-Systems Ltd | Wholesale & retail | 2017 |
| L'Artisan Deli Limited | Hospitality | 2020 |
| L'Artisan Foods Limited | Wholesale & retail | 2013 |
| L.J. Machine Tools Limited | Wholesale & retail | 1979 |
| L.J. Protective Coatings Ltd | Wholesale & retail | 1994 |
| LA Cards & Gifts Ltd | Wholesale & retail | 2024 |
| LA MON Investments Limited | Real estate | 2025 |
| La-Morks Technologies PVT Ltd | Information & communication | 2023 |
| LAB App Ltd | Information & communication | 2024 |
| Lacehill Management Limited | Households | 2014 |
| Lagan Gate Management Limited | Households | 2014 |
| Lagan Rivers Trust | Information & communication | 2012 |
| Lake Road Services Ltd | Wholesale & retail | 2017 |
| Lakeview Fitness Ltd | Arts & recreation | 2024 |
| Lakeview Meadow Management Company Limited | Households | 2018 |
| Lamph Family Investments Limited | Professional & scientific | 2020 |
| Lance Mechanical Services Limited | Construction | 2017 |
| Lancullen Ltd | Real estate | 2021 |
| Land Dallas Limited | Construction | 2019 |
| Land of Lizards Ltd | Wholesale & retail | 2020 |
| Landed Property Ltd | Real estate | 2023 |
| Landedhq Ltd | Information & communication | 2026 |
| Landfill Services Limited | Water & waste | 2018 |
| Landman Property Solutions Ltd | Real estate | 2026 |
| Landscape Supplies (NI) Limited | Wholesale & retail | 2012 |
| Lane Framing Ltd | Wholesale & retail | 2017 |
| Laney (NI) Limited | Real estate | 2014 |
| Langford Technology Ltd | Information & communication | 2021 |
| Langtry Lane Ltd | Wholesale & retail | 2024 |
| Lappin Engineering Limited | Manufacturing | 2005 |
| Larden Lite Ltd | Financial services | 2023 |
| Larman Ridge Ltd | Construction | 2020 |
| Larman Ridge Property Investments Ltd | Financial services | 2020 |
| Larman Ridge Services Ltd | Construction | 2020 |
| Larne Bingo Limited | Arts & recreation | 2025 |