| Kiltybaneinternational Ltd | Transport & logistics | 2020 |
| Kinallen Road Management Limited | Households | 2025 |
| King & Castillo Ltd | Real estate | 2014 |
| King Storage Limited | Wholesale & retail | 2017 |
| Kingport Trade L.P. | | 2017 |
| Kingsbrook Shoes Ltd | Wholesale & retail | 2025 |
| Kingsmill Farm Supplies Limited | Wholesale & retail | 2010 |
| Kingsmill Farms Limited | Agriculture & fishing | 2005 |
| Kingsmill Finance Ltd | Financial services | 2012 |
| Kintrella Limited | Real estate | 2013 |
| Kirchel Couture Limited | Wholesale & retail | 2015 |
| Kirchel Property Ltd | Real estate | 2021 |
| Kirsty’S Kloset Limited | Wholesale & retail | 2021 |
| Kitchen Misfits Ltd | Hospitality | 2025 |
| Kitchen Operating System Ltd | Information & communication | 2014 |
| Kitchen OS Technologies Ltd | Information & communication | 2026 |
| Kitchingham Meats Ltd | Manufacturing | 2022 |
| Kitsar Ltd | Other services | 2025 |
| KJ Industry Ltd | Hospitality | 2026 |
| KJ Transport (2021) Ltd | Transport & logistics | 2021 |
| KJG Contracts Ltd | Construction | 2024 |
| KKT Transport Ltd | Transport & logistics | 2026 |
| Klas Inc Limited | Administrative & support | 2025 |
| KLC Transport IRL Limited | Transport & logistics | 2014 |
| KLC Transport Limited | Transport & logistics | 2024 |
| KLM Brows and Makeup Ltd | Other services | 2023 |
| KM Contracts Ltd | Construction | 2021 |
| KM Euro Freight Ltd | Transport & logistics | 2017 |
| KM GAS & Services Ltd | Energy | 2010 |
| KM Survey Solutions Ltd | Professional & scientific | 2022 |
| KMC Brick & Block Contracts Limited | Construction | 2019 |
| KMC Transport (Ireland) Limited | Transport & logistics | 2014 |
| Kmcg Golf Limited | Arts & recreation | 2024 |
| KMG Performance Ltd | Health & social care | 2013 |
| KMH N.I. Limited | Wholesale & retail | 2020 |
| KMK Innovation Holdings Ltd | Financial services | 2025 |
| KMK Metals Recycling Limited | Water & waste | 2025 |
| KMR Consultants Ltd | Professional & scientific | 2025 |
| Kmts Holdings Limited | Financial services | 2023 |
| KN Haulage Limited | Transport & logistics | 2015 |
| Kneecap Drinks Ltd | Wholesale & retail | 2026 |
| Knight Structural Engineering Limited | Construction | 2024 |
| Knights Templar International Novus Ordo Militiae Limited | Other services | 2015 |
| KNJ Ltd | Real estate | 2019 |
| Knockdarragh Property Management Ltd | Real estate | 2002 |
| Knockout Competitions Limited | Arts & recreation | 2025 |
| Know Yourself Performance Ltd | Education | 2020 |
| Knox Grocery Group Ltd | Professional & scientific | 2025 |
| Kociu 2025 Limited | Hospitality | 2025 |
| Koffy Limited | Wholesale & retail | 2026 |
| KOH Bricklaying Ltd | Construction | 2018 |
| KOH Consultancy Ltd | Professional & scientific | 2020 |
| KOH Electrical Limited | Construction | 2019 |
| Kohare Consultancy Limited | Construction | 2022 |
| Kohl Florian Ltd | Wholesale & retail | 2024 |
| Konvi Holdings Limited | Financial services | 2021 |
| Korgan Investments Ltd | Real estate | 2018 |
| Kosi Corporation Limited | Professional & scientific | 2010 |
| Kosi Group Limited | Information & communication | 2024 |
| Kota Management Consulting Ltd | Administrative & support | 2024 |
| Kova Combat Ltd | Arts & recreation | 2025 |
| KPM Freight Ltd | Transport & logistics | 2017 |
| KPM Joinery Limited | Construction | 2021 |
| KPM Logistics Limited | Transport & logistics | 2011 |
| KPP Developments Ltd | Construction | 2014 |
| KR Mechanical Limited | Manufacturing | 2010 |
| Kraigher Emergency Medicine | Health & social care | 2026 |
| Kram Sales Ltd | Wholesale & retail | 2017 |
| Krem Properties Limited | Real estate | 2019 |
| Kroon Properties Limited | Real estate | 2017 |
| Kroth Andrea Ltd | Wholesale & retail | 2024 |
| KS Tiling Ltd | Construction | 2021 |
| KSD Energy Ltd | Energy | 2016 |
| KSD Properties Ireland Ltd | Real estate | 2023 |
| KSH Engineering & Commodities Ltd | Manufacturing | 2016 |
| KT OIL Ltd | Wholesale & retail | 2005 |
| Kukoon Retail Ltd | Wholesale & retail | 2017 |
| Kukoon Rugs Limited | Wholesale & retail | 2011 |
| Kwim Ltd | Other services | 2021 |
| KWM Supplies Ltd | Wholesale & retail | 2018 |
| KX Software I Limited | Professional & scientific | 2016 |
| KX Software Services Limited | Professional & scientific | 2017 |
| KX Systems Ltd | Financial services | 2022 |
| KYC Ireland Limited | Other services | 2024 |
| L & a Valley Ltd | Extraterritorial | 2023 |
| L Mcbride Contracts Limited | Agriculture & fishing | 2016 |
| L Mccooey Ltd | Hospitality | 2013 |
| L&B Daycare Ltd | Health & social care | 2022 |
| L.A.P.M Electrical Ltd | Construction | 2017 |
| LA Mechanical Ltd | Professional & scientific | 2024 |
| LA Steel Fabrications Limited | Manufacturing | 2017 |
| Lady T'S Boutique Ltd | Wholesale & retail | 2012 |
| LAF Hair & Beauty Ltd | Other services | 2022 |
| Lagan Foods Ltd | Construction | 2023 |
| Lagan Ssdab Limited | Information & communication | 2017 |
| Laganmore Limited | Professional & scientific | 2010 |
| LAJ Group Ltd | Wholesale & retail | 2023 |
| Lake Sales LP | | 2017 |
| Lakemont Export L.P. | | 2017 |
| Lakeside Camlough Ltd | Construction | 2023 |