| Lightfoot Cleaning Services Ltd | Administrative & support | 2024 |
| Lindop Brothers (Queensferry) Limited | Extraterritorial | 1969 |
| Lindop Brothers (Wrexham) Limited | Extraterritorial | 1980 |
| Linens and Curtains Limited | Wholesale & retail | 2021 |
| Linez Ltd | Other services | 2024 |
| Lingley Estates Limited | Professional & scientific | 2005 |
| LIP Medical Limited | Health & social care | 2010 |
| Little Roodee Estate Management Company Limited | Other services | 2004 |
| Little Stars (Deeside) Limited | Education | 2008 |
| Livewells Global Limited | Other services | 2014 |
| Living Shutters Limited | Construction | 2015 |
| Liza Barber Ltd | Other services | 2024 |
| LJB Property Investment Ltd | Real estate | 2019 |
| Ljhr Consulting Limited | Other services | 2024 |
| LK Solutions Ltd | Professional & scientific | 2025 |
| Lloyd-Davies Garden Services Limited | Administrative & support | 2020 |
| LMF Properties Ltd | Real estate | 2015 |
| Locit Limited | Manufacturing | 2021 |
| Lodge Initiatives Holdings Ltd | Financial services | 2021 |
| Lodge Initiatives Ltd | Wholesale & retail | 2002 |
| Lotus Business Services Ltd | Administrative & support | 2021 |
| Lovelock Renewables Limited | Construction | 2024 |
| Loyaldrive Limited | Real estate | 1995 |
| LR Chemical Consultancy Limited | Professional & scientific | 2018 |
| LT Shoreditch Limited | Hospitality | 2016 |
| LTP Express Ltd | Transport & logistics | 2026 |
| LTS Driving School Ltd | Education | 2026 |
| LTU OIL Limited | Water & waste | 2025 |
| Luke Thomas Dining Company Limited | Professional & scientific | 2016 |
| Luke Thomas Events Limited | Hospitality | 2015 |
| Luke Thomas Limited | Professional & scientific | 2011 |
| Luna Creative Design Limited | Professional & scientific | 2019 |
| Luscious Lengths Ltd | Wholesale & retail | 2016 |
| LUX Nails & Spa Deeside Ltd | Other services | 2025 |
| Luxury Nails & Spa HA Ltd | Other services | 2026 |
| LW Electrical Services Ltd | Manufacturing | 2020 |
| Lykke Rental Homes Ltd | Real estate | 2021 |
| M C Owens Ltd | Professional & scientific | 2025 |
| M J Woods Interim Ltd | Other services | 2024 |
| M R Driveways Ltd | Administrative & support | 2025 |
| M.E.S.Powersports Limited | Manufacturing | 2006 |
| M.S.B. Limited | Professional & scientific | 1981 |
| MAA Moo’S Ltd | Hospitality | 2025 |
| Maaya Homes Limited | Construction | 2019 |
| MAC Dwellings Ltd | Extraterritorial | 2021 |
| Machine Learnia Ltd | Wholesale & retail | 2022 |
| Macika Limited | Wholesale & retail | 2018 |
| Macodape Investments Ltd | Financial services | 2017 |
| Maculric Properties (DS) Limited | Real estate | 2025 |
| Maculric Properties Limited | Construction | 2025 |
| MAISON8 Ltd | Construction | 2025 |
| Majestic Corporation P.L.C. | Water & waste | 2021 |
| Malad Ltd | Professional & scientific | 2026 |
| Malive UK Limited | Transport & logistics | 2026 |
| Mane Investments Ltd | Real estate | 2015 |
| Mara Electrical Ltd | Construction | 2010 |
| Mara Holdings Limited | Financial services | 2024 |
| Mara Property & Investments Limited | Real estate | 2024 |
| Marketing in Motion Ltd | Professional & scientific | 2021 |
| Mass Realty Ltd | Real estate | 2023 |
| Mata Group Ltd | Arts & recreation | 2024 |
| Matty’S Installations Ltd | Construction | 2023 |
| Mavic Commercial Garages Ltd | Wholesale & retail | 2024 |
| Mavic Commercial Vehicle Solutions Limited | Wholesale & retail | 2009 |
| Maxi Products Limited | Wholesale & retail | 2017 |
| Mbezeli Interprises Ltd | Households | 2025 |
| Mbsignalling Limited | Professional & scientific | 2022 |
| MC Supplies (NW) Ltd | Wholesale & retail | 2025 |
| Mccormick Architecture Limited | Professional & scientific | 2004 |
| Mcdonald BJJ Limited | Arts & recreation | 2015 |
| Mcgowan Site Services Limited | Administrative & support | 2012 |
| MCH Electrical Services Ltd | Other services | 2024 |
| ME Cosmetics Limited | Professional & scientific | 2002 |
| MEA UK Limited | Wholesale & retail | 1993 |
| Measured Supplements Ltd | Wholesale & retail | 2026 |
| Mediterranean Limited | Hospitality | 2026 |
| Meiller Lift Doors UK Limited | Wholesale & retail | 2024 |
| Meiller-Boweld UK Limited | Manufacturing | 2006 |
| Melbreck Investments Limited | Financial services | 2026 |
| Mellowday Ltd | Wholesale & retail | 2022 |
| Melrose Inn Limited | Hospitality | 2006 |
| Menorah Massage Ltd | Health & social care | 2021 |
| Mercan Cafe Ltd | Hospitality | 2026 |
| MGS - Direct Ltd | Real estate | 2002 |
| MH Engineering & Maintenance Ltd | Professional & scientific | 2023 |
| MH GAS & Bathrooms Limited | Construction | 2018 |
| Michael Owen Racing Club Ltd | Arts & recreation | 2018 |
| Miles Jones Ltd | Professional & scientific | 2025 |
| Milldown Estates Limited | Construction | 2013 |
| Milton Sustainable Development Services Ltd | Professional & scientific | 2023 |
| Minshull Windows Limited | Construction | 2008 |
| Miras Transport Ltd | Transport & logistics | 2016 |
| Mixed European Store Ltd | Wholesale & retail | 2024 |
| Mjascc Limited | Professional & scientific | 2017 |
| MJT Transport Ltd | Transport & logistics | 2026 |
| MKR91 Ltd | Transport & logistics | 2021 |
| MM Packaging Deeside Ltd | Administrative & support | 1992 |
| MO Car Sales Ltd | Wholesale & retail | 2023 |
| Mocanas Ltd | Construction | 2019 |
| Modelme Management Limited | Other services | 2015 |