| Ladyhill Holdings Limited | Professional & scientific | 1986 |
| Lagan River Limited | Real estate | 2022 |
| Lagan River Portfolio Ltd | Real estate | 2014 |
| Lain's Kitchen Limited | Hospitality | 2024 |
| Lamplighter Residential Ltd | Real estate | 2025 |
| Landgray Ltd | Households | 2024 |
| Lava Auto Ltd | Wholesale & retail | 2023 |
| Lavery Properties Ltd | Real estate | 1997 |
| Lawsearch NI Ltd | Other services | 2021 |
| Lazy Claire Patisserie Limited | Manufacturing | 2017 |
| Lazy Swine Ltd | Hospitality | 2019 |
| LBN Homecare Services Ltd | Health & social care | 2023 |
| LCP Kitchens Limited | Other services | 2023 |
| LEE Austin Design Ltd | Professional & scientific | 2022 |
| Leeu Limited | Hospitality | 2024 |
| Leighinmohr Crescent Management Company Limited | Households | 2008 |
| Leja Enterprises Limited | Real estate | 2017 |
| Leja Properties Limited | Real estate | 2017 |
| Lekker Beauty Ltd | Other services | 2010 |
| Lenel Properties LLP | | 2007 |
| Leskard Ltd | Wholesale & retail | 2023 |
| Lestorg Limited | Construction | 2020 |
| LHK Aesthetics Ltd | Other services | 2023 |
| Lickisto GB Ltd | Hospitality | 2018 |
| Lidor Limited | Professional & scientific | 2019 |
| Lightbulb Teams Limited | Administrative & support | 2019 |
| Lighthouse N.I. Ltd | Professional & scientific | 2012 |
| Like Studio Limited | Administrative & support | 2024 |
| Line Undrawn Ltd | Professional & scientific | 2024 |
| Linen Lofts Management Limited | Households | 2002 |
| Lion Rock Ventures Limited | Professional & scientific | 2020 |
| Little Titans LL Ltd | Real estate | 2026 |
| LMW Developments Ltd | Real estate | 2016 |
| Lnfitz Limited | Professional & scientific | 2018 |
| Loada Balls Events Ltd | Hospitality | 2026 |
| Local Automotive Ltd | Wholesale & retail | 2023 |
| Local Carparks Limited | Real estate | 1985 |
| Lonely Street Discs Ltd | Information & communication | 2024 |
| Longbridge House Limited | Real estate | 2015 |
| Lorne Cottages Craigavad Management Company Limited | Extraterritorial | 2020 |
| Louise Maguire Coaching Ltd | Professional & scientific | 2025 |
| Lowburn Properties Limited | Professional & scientific | 2005 |
| LPM (N.I.) Ltd | Professional & scientific | 2017 |
| LR Residential Limited | Real estate | 2014 |
| Ludik Design Ltd | Real estate | 2017 |
| Luminosity Ltd | Professional & scientific | 2024 |
| Luxury Diamonds Ltd | Wholesale & retail | 2017 |
| Luxury Tanning Ltd | Other services | 2015 |
| Lyle Motors (Newtownards) Limited | Wholesale & retail | 1964 |
| Lynch Advisory Services Limited | Professional & scientific | 2024 |
| Lynchpin Holywood Ltd | Hospitality | 2020 |
| M&G Rentals Limited | Real estate | 2025 |
| M. Bullick & Sons (Decorators) Limited | Real estate | 1962 |
| M.C.W. Properties Limited | Real estate | 1989 |
| Madair Consultants Ltd | Arts & recreation | 2024 |
| Mady Properties Ltd | Real estate | 2021 |
| Maeve Macdonald Psychology Services Ltd | Education | 2024 |
| Maliz Consulting Limited | Construction | 2005 |
| Maliz Developments Limited | Administrative & support | 2007 |
| Mangal Maye NI Limited | Real estate | 2025 |
| Manna Finance (NI) Limited | Administrative & support | 2024 |
| Manor House Regeneration Ltd | Construction | 2026 |
| MAP Cover Limited | Information & communication | 2017 |
| Margin Architecture & Planning Ltd | Professional & scientific | 2026 |
| Marianne Trust | Administrative & support | 2000 |
| Mark Faulkner People Development Ltd | Administrative & support | 2017 |
| Marley Bay Investments Ltd | Real estate | 2020 |
| Marmont Properties Holdings Limited | Real estate | 2019 |
| Marmont Properties Limited | Real estate | 2019 |
| Marram Aberlady LLP | | 2022 |
| Marram Bushmills LLP | | 2020 |
| Marram Hotel Partners Limited | Hospitality | 2022 |
| Marram Hotels Limited | Hospitality | 2022 |
| Marram Newcastle LLP | | 2024 |
| Marram Playfair LLP | | 2022 |
| Marram Southport LLP | | 2022 |
| Marram WFX Limited | Financial services | 2020 |
| Marshel Advisory Ltd | Professional & scientific | 2024 |
| Martello Gate Limited | Households | 2021 |
| Martello Lands Ltd | Construction | 2020 |
| Mary T Ltd | Information & communication | 2018 |
| Mash Comms Limited | Professional & scientific | 2018 |
| Massall (NI) Limited | Financial services | 2021 |
| MAX DEV. Ltd | Real estate | 1998 |
| Mayne Fitness Limited | Arts & recreation | 2022 |
| MCA Medical Devices Ltd | Professional & scientific | 2013 |
| Mccloymac Property Limited | Real estate | 2024 |
| Mccormick Fleet Solutions Limited | Administrative & support | 2017 |
| Mccotter Agencies Limited | Administrative & support | 2007 |
| Mccreery Holdings International Limited | Construction | 2026 |
| Mccullough Residential Ltd | Real estate | 2020 |
| Mcguinness Fleck Estate Agents Ltd | Households | 2014 |
| Mcguinness Fleck Ltd | Real estate | 2003 |
| Mckinney Estates Ltd. | Real estate | 2011 |
| Mclaughlin Hospitality Limited | Other services | 2021 |
| Mcleese Cottages Management Company Limited | Households | 2003 |
| Mcmurray Medicolegal Ltd | Health & social care | 2020 |
| MCW Distribution Ltd | Arts & recreation | 2005 |
| Mediation Reconciliation and Advocacy Services Ltd | Professional & scientific | 2024 |
| Medidesign Limited | Manufacturing | 2016 |