| Livingston Dental Healthcare Limited | Health & social care | 2013 |
| Livlast Ltd | Wholesale & retail | 2013 |
| LJ Heavy Lifting Limited | Construction | 2025 |
| LJH Vehicle Services Limited | Wholesale & retail | 2025 |
| LKD Surveying and Consulting Ltd | Professional & scientific | 2022 |
| LL57 CBC | Arts & recreation | 2026 |
| Llaisdy CYF | Information & communication | 2011 |
| LLAMAS33 Ltd | Hospitality | 2024 |
| LLE Cyfyngedig | Real estate | 1988 |
| Llesiant DA Wellness CYF | Health & social care | 2023 |
| Llety CYF | Real estate | 2022 |
| Llewac CYF | Real estate | 2023 |
| Llewelyn FÔN CYF | Hospitality | 2019 |
| Lloriau JC Flooring Limited | Construction | 2015 |
| Llwynpenddu Isaf Holidays CYF | Hospitality | 2025 |
| LM Property Consulting Ltd | Real estate | 2018 |
| Lnayres Limited | Hospitality | 2025 |
| Locked Productions Limited | Information & communication | 2025 |
| Loftholdingswood Ltd | Information & communication | 2026 |
| Logic FP Ltd | Professional & scientific | 2013 |
| Logie Green Limited Partnership | | 2012 |
| LON Trwy'R Coed (LTC) CYF. | Administrative & support | 2021 |
| London Garage Limited | Wholesale & retail | 2006 |
| Long Runs the FOX Films Ltd | Arts & recreation | 2016 |
| Lonrú Consulting Ltd | Professional & scientific | 2024 |
| Lorelei Apartments Limited | Extraterritorial | 2000 |
| Loreley Ltd | Hospitality | 2020 |
| Losty Property Ltd | Real estate | 2025 |
| Lotus Lounge Spa Limited | Other services | 2026 |
| Loughran Foods Ltd | Hospitality | 2016 |
| Loughview Properties Ltd | Construction | 2000 |
| Lower Bristol Road Bath Limited | Construction | 2019 |
| LPC Leisure Ltd | Wholesale & retail | 2007 |
| LPS Nottingham Limited | Construction | 2021 |
| Lucas Student Lettings Limited | Real estate | 2015 |
| Lucas-Pedigrew Partnership Ltd | Professional & scientific | 2002 |
| Luck of the Draw Competitions Ltd | Wholesale & retail | 2024 |
| LUI Developments Limited | Hospitality | 2011 |
| Luke Electrical Services Limited | Construction | 2021 |
| Luxurious Linen Hire Ltd | Other services | 2019 |
| Lwid Ltd | Professional & scientific | 2021 |
| LWO Electrical Ltd | Construction | 2024 |
| Lynda Jacobs Recruitment Ltd | Administrative & support | 2018 |
| M & J Developments Ltd | Real estate | 2005 |
| M & M Construction (N.W.) Ltd. | Real estate | 1988 |
| M G Couriers (2021) Ltd | Transport & logistics | 2021 |
| M Hughes & SON Limited | Construction | 2014 |
| M T Sykes (Contracting) Limited | Construction | 2007 |
| M&Lcochraneproperty Ltd | Hospitality | 2026 |
| M&S Mobiles Limited | Wholesale & retail | 2019 |
| M. Timoney Limited | Wholesale & retail | 1985 |
| M.A.V. Legal Solutions Limited | Professional & scientific | 2016 |
| Mabinogion 888 Ltd | Hospitality | 2025 |
| Macar Property Development and Lettings Limited | Construction | 2024 |
| Maclennan Construction Limited | Construction | 2003 |
| Macquarie Property Investments Ltd | Real estate | 2024 |
| Madeforyousf Ltd | Hospitality | 2026 |
| Madison Loft Living Limited | Construction | 2023 |
| Maesg Showzone CIC | Arts & recreation | 2024 |
| Maesni C,L,G Limited | Health & social care | 2023 |
| Maggie's African Twist Limited | Agriculture & fishing | 2022 |
| Magpie Bricks Ltd | Wholesale & retail | 2023 |
| Mahema Consult Ltd | Professional & scientific | 2023 |
| Mail Metrics Business Services UK Limited | Administrative & support | 2001 |
| Main MAN PVT Ltd | Other services | 2023 |
| Mairead & Co Interiors Limited | Professional & scientific | 2023 |
| Majj Properties | Real estate | 2012 |
| Make Information Technology Work LP | | 2016 |
| Make IT Work Ltd | Information & communication | 2022 |
| Malachy O Edwards Limited | Arts & recreation | 2024 |
| Malago Road Bristol Limited | Construction | 2022 |
| Malibu Properties Limited | Real estate | 2000 |
| Manage My Home Ltd | Health & social care | 2026 |
| Manasseh$Miriam Stores Ltd | Wholesale & retail | 2025 |
| Mango Direct Marketing Ltd | Administrative & support | 2008 |
| Mango Estates Ltd | Real estate | 2012 |
| Mango Films Limited | Information & communication | 2002 |
| Mango Group (N.I.) Ltd | Administrative & support | 2012 |
| Manor Apartments Limited | Extraterritorial | 1993 |
| Marcel the Cat Ltd | Hospitality | 2024 |
| Marifi Limited | Wholesale & retail | 2026 |
| Marilotte Limited | Professional & scientific | 2021 |
| Marimel Ltd | Hospitality | 2012 |
| Marine Imports UK Limited | Wholesale & retail | 2007 |
| Market Court Management Limited | Extraterritorial | 1989 |
| Marketdock Ltd | Wholesale & retail | 2021 |
| Marlen Media Entertainment Ltd | Wholesale & retail | 2018 |
| Marleypol Properties Ltd | Real estate | 2023 |
| Marquis Manor Management Company Ltd | Households | 1999 |
| Marquisate Rental and Property Management Limited | Real estate | 2009 |
| Marrac Design Ltd | Construction | 2019 |
| Marshwell Developments Ltd | Construction | 2025 |
| Maryville Park Management Company Ltd | Extraterritorial | 2011 |
| Masala Monsoon Ltd | Hospitality | 2026 |
| MAT the HAT Limited | Manufacturing | 2025 |
| Matfield Business Services Limited | Administrative & support | 2021 |
| Mathew Nottingham CYF | Construction | 2023 |
| Matrix Planning Consultancy Ltd | Arts & recreation | 2025 |
| Matthew Taylor Jones Ltd | Transport & logistics | 2025 |
| Mauds Temptations Ltd | Hospitality | 2023 |