| Kels Original Ltd | Wholesale & retail | 2020 |
| Kelson Retail Ltd | Wholesale & retail | 2019 |
| Kenash Consulting | Professional & scientific | 2020 |
| Kennedy Property Developments Limited | Real estate | 2001 |
| Kerkel Limited | Real estate | 2025 |
| KES Construction (N.I.) Limited | Construction | 2016 |
| Kesh Road Developments Ltd | Real estate | 2022 |
| Kidd-Z-Play Limited | Health & social care | 2013 |
| Kiddiwinkles Daycare Limited | Health & social care | 2015 |
| Kieran Letters Plumbing & Heating Ltd | Construction | 2018 |
| Kilcronaghan Mission Hall Ltd | Other services | 2021 |
| Killeen Country Stores Ltd | Wholesale & retail | 2020 |
| Killyberry Property Limited | Real estate | 2025 |
| Killypark Ltd | Real estate | 2018 |
| Kinrush Ltd | Hospitality | 2026 |
| KM Freight Forwarding Ltd | Transport & logistics | 2026 |
| Kmac Mechanical Ltd | Construction | 2016 |
| Kmbc Properties Limited | Construction | 2006 |
| KMC Engineering (NI) Ltd | Manufacturing | 2000 |
| Knightswood Properties Limited | Real estate | 2015 |
| Knockloe Holdings Ltd | Financial services | 2016 |
| Knocknagin Hall Committee | Education | 2017 |
| Konect Electrical NI Ltd | Construction | 2024 |
| Korporate Kids Limited | Real estate | 2002 |
| Korporate Services Ltd | Professional & scientific | 2011 |
| Korwind Ltd | Professional & scientific | 2015 |
| KS Dental Holdings Ltd | Health & social care | 2025 |
| Kymeca Limited | Information & communication | 2026 |
| Kyzara Hire Limited | Administrative & support | 2022 |
| Kyzara Holdings Limited | Financial services | 2022 |
| Labby Property Services Ltd | Construction | 2022 |
| Lagan Bros Limited | Administrative & support | 2020 |
| Lagan Utilities Limited | Construction | 2017 |
| Lagquip Ltd | Agriculture & fishing | 2024 |
| Laharna Retail Park Ltd | Real estate | 2018 |
| Laragh Developments Limited | Construction | 2005 |
| Larchwood Care (NI) Limited | Health & social care | 2013 |
| Laurelhill Joinery Ltd | Construction | 2019 |
| Lauren Toal Brand & Marketing Ltd | Professional & scientific | 2025 |
| Lavender Drive Company Limited | Extraterritorial | 2024 |
| Lavender Way Company Limited | Extraterritorial | 2026 |
| LB (Ireland) Ltd | Real estate | 2018 |
| LE Vier Ltd | Wholesale & retail | 2024 |
| Lefety Investments | Professional & scientific | 2014 |
| Leitrim Group Holdings Ltd | Financial services | 2025 |
| Leitrim NO 1 Ltd | Construction | 2023 |
| Lentrad Ltd | Professional & scientific | 2015 |
| Letteran Ltd | Hospitality | 2020 |
| Lime Heights Company Limited | Extraterritorial | 2022 |
| Limestone Business Park Ltd | Real estate | 2025 |
| Linen Workers CIC | Manufacturing | 2025 |
| Lisnafin Developments Limited | Administrative & support | 2005 |
| Littlebridge Farm Fresh Ltd | Wholesale & retail | 2021 |
| Littlebridge Investments Ltd | Manufacturing | 2011 |
| Littlebridge Takeaway Ltd | Hospitality | 2022 |
| LMC Chartered Accountants Ltd | Professional & scientific | 2023 |
| LN Partnership C.I.C. | Professional & scientific | 2018 |
| Lobster and Lime Limited | Hospitality | 2025 |
| Lochkeen Ltd | Professional & scientific | 2022 |
| Lochtillagh Limited | Hospitality | 2005 |
| Loco Property Group Ltd | Real estate | 2024 |
| Lodge Renewables Limited | Energy | 2011 |
| Loncto Limited | Wholesale & retail | 2025 |
| Longfield Haulage Limited | Transport & logistics | 1994 |
| Longfield More Management Limited | Wholesale & retail | 2024 |
| Lorken Ltd | Construction | 2015 |
| Louelle Designs Ltd | Professional & scientific | 2024 |
| Lough Erne Hotel Limited | Administrative & support | 1973 |
| Loughdoyle Construction Limited | Construction | 2013 |
| Loughran Construction Limited | Construction | 2011 |
| Loughshore Marina Cafe Limited | Hospitality | 2023 |
| Loughshore Security Ltd | Administrative & support | 2025 |
| Loves Hospitality Ltd | Hospitality | 2022 |
| Loves Road Property Limited | Financial services | 2022 |
| Lucky Dragon Magherafelt Ltd | Hospitality | 2025 |
| Lulkjfzgs Limited | Wholesale & retail | 2025 |
| Luney Mill Properties Limited | Real estate | 2022 |
| Lurganagoose Services Ltd | Professional & scientific | 2016 |
| Lurgyroe Enterprises | Financial services | 2026 |
| M a Cooper Ltd | Construction | 2022 |
| M&D Electrics Limited | Construction | 2002 |
| M-Consult Services Ltd | Professional & scientific | 2021 |
| M. Doyle Contracts Ltd | Construction | 2004 |
| M.J. Mcbride Construction Ltd | Construction | 2007 |
| M.T Renewables Ltd. | Energy | 2016 |
| MA Browns Catering (2022) Ltd | Hospitality | 2022 |
| Ma.Guttering Ltd | Construction | 2026 |
| MAC Automation (N.I.) Limited | Administrative & support | 2019 |
| MAC Properties UK & Ireland Ltd | Real estate | 2022 |
| Macca Studios Limited | Wholesale & retail | 2025 |
| Macca Ventures Limited | Financial services | 2025 |
| Maccon (NI) Ltd | Construction | 2003 |
| Macdc Electrics Ltd | Construction | 2012 |
| Macro Property Solutions Ltd | Professional & scientific | 2023 |
| Madden Dental Ltd | Health & social care | 2015 |
| Magherafelt & District Motor Club Limited | Arts & recreation | 1983 |
| Magherafelt Business Park Limited | Real estate | 2019 |
| Magherafelt Chamber of Commerce | Other services | 2011 |
| Magherafelt Healthcare Ltd | Wholesale & retail | 2015 |
| Magherafelt Nails & Spa Ltd | Other services | 2025 |