| Kids in Nature Ltd | Wholesale & retail | 2019 |
| Kilfrew Consult Ltd | Professional & scientific | 2016 |
| Kimkat Ltd | Hospitality | 2025 |
| Kings Head USK Limited | Hospitality | 2023 |
| Knowle Meadow Camping Limited | Hospitality | 2024 |
| L J Hawkins & SON Bespoke Joinery & Aluminium Systems Limited | Manufacturing | 2025 |
| L&D Pubs Ltd | Hospitality | 2020 |
| Laluna Media Ltd | Professional & scientific | 2019 |
| Lansdales Ltd | Real estate | 1985 |
| Lavinia's Farm Ltd | Agriculture & fishing | 2026 |
| Lemmiout Activities Ltd | Education | 2018 |
| Lens School Evaluation Ltd | Education | 2021 |
| Level Facilities Management Limited | Construction | 1999 |
| Lewis Pharmacy Limited | Wholesale & retail | 2000 |
| Little Dinos Role Play Centre Ltd | Health & social care | 2020 |
| Livewire Electronic Components Limited | Wholesale & retail | 1995 |
| LIZ Crawford Consultancy Limited | Administrative & support | 2025 |
| Llansoy Events Limited | Arts & recreation | 2024 |
| Llansoy Scientific Ltd | Professional & scientific | 2024 |
| Llanunwas Community Limited | Hospitality | 2014 |
| Lloyd Bennett (Coins of Britain) Limited | Wholesale & retail | 2012 |
| Llwyn Celynnen CYF | Energy | 2012 |
| Llys Tadcu Management Company Limited | Real estate | 1997 |
| LOC Plant Ltd | Real estate | 2013 |
| Lohfink Medical Services Limited | Administrative & support | 2013 |
| London BUS 4 Hire Ltd. | Transport & logistics | 2010 |
| Louise Light Accessories Limited | Wholesale & retail | 2025 |
| LRW Motor Company Limited | Wholesale & retail | 2022 |
| Luca at the Lodge Ltd | Hospitality | 2025 |
| Lvbt Limited | Transport & logistics | 2026 |
| Lymax Holdings Limited | Wholesale & retail | 2020 |
| M K Asset Management Ltd | Financial services | 2018 |
| M. P. Kenyon Limited | Health & social care | 2007 |
| M.J. Gallimore Consulting Limited | Professional & scientific | 2018 |
| MAC 62 Group Limited | Professional & scientific | 2007 |
| MAC62 Consulting Ltd | Professional & scientific | 2017 |
| Maddock Properties Limited | Extraterritorial | 2010 |
| Madoc Marine Ltd | Professional & scientific | 2014 |
| MAN ENG Solutions Limited | Professional & scientific | 2021 |
| Mariners Port Isaac Limited | Real estate | 2022 |
| Mark Coray & Co Limited | Other services | 2023 |
| Market Garden Flower Co Ltd | Wholesale & retail | 2022 |
| Market Street Service Station Ltd | Wholesale & retail | 2019 |
| Markit Consulting Limited | Information & communication | 2016 |
| Marsland Service Station Ltd | Wholesale & retail | 2019 |
| Martin Turner Associates Limited | Professional & scientific | 2009 |
| Matriarch Minerals UK Limited | Mining & quarrying | 2025 |
| Mcgovern Chang Limited | Real estate | 2019 |
| Mears-Inc Ltd | Construction | 2016 |
| MEC Industrial Engineering Ltd | Manufacturing | 2013 |
| Medaxis Consulting Ltd | Professional & scientific | 2026 |
| Merchant Equity Limited | Real estate | 2002 |
| Merricon Limited | Professional & scientific | 1983 |
| Merton-Williams Metal Company Limited | Manufacturing | 2006 |
| MGI Motorbroker.Co.Uk Ltd | Wholesale & retail | 2017 |
| MGI Network Ltd | Financial services | 2011 |
| MHB Innovations Ltd | Agriculture & fishing | 2021 |
| Mike Glavin Catalyst Limited | Education | 2020 |
| Mitch & Lynn Star Restaurant Limited | Hospitality | 2022 |
| Mitchell Marquees Ltd | Administrative & support | 2017 |
| MJP Building Surveying Consultancy Ltd | Professional & scientific | 2025 |
| Monmouth OFF Street Project | Arts & recreation | 2015 |
| Monmouthshire Property Maintenance and Services Ltd | Construction | 2019 |
| Montcliffe Commercial Services Limited | Information & communication | 2015 |
| Morgan T Vowles Limited | Other services | 2008 |
| Morris's Grounds Maintenance Limited | Other services | 2007 |
| Morris's of USK Garden Centre and Nurseries Limited | Wholesale & retail | 2016 |
| Moseley Technical Services Limited | Professional & scientific | 2002 |
| MSH82 Holdings 2 Limited | Real estate | 2025 |
| MSR Finance Consultancy Limited | Professional & scientific | 2020 |
| Mulberry Orthopaedics Limited | Health & social care | 2017 |
| Muuk Activities Limited | Arts & recreation | 2023 |
| Muuk Adventures Limited | Arts & recreation | 2016 |
| My Beau Limited | Hospitality | 2015 |
| MÖR Holdings Limited | Administrative & support | 2019 |
| MÖR International Ltd. | Manufacturing | 2019 |
| MÖR Studios Ltd. | Professional & scientific | 2019 |
| N D Lewis & SON Limited | Wholesale & retail | 2014 |
| Napier Catering Holdings Limited | Financial services | 2019 |
| Napier Catering Limited | Hospitality | 2003 |
| Nash Groundworks and Landscapes Ltd | Construction | 2015 |
| Nash Michaels Ltd | Professional & scientific | 2023 |
| Natural and Welsh Candles Ltd | Manufacturing | 2013 |
| Natural GIN Selection Limited | Wholesale & retail | 2025 |
| New World Odour Ltd | Information & communication | 2020 |
| Newgem Limited | Transport & logistics | 2013 |
| Nicola Fisher Limited | Hospitality | 2007 |
| Normandy Holdings Limited | Professional & scientific | 2002 |
| Numbers & Music Limited | Other services | 2008 |
| Nurture One UK Ltd | Construction | 2023 |
| Oakfern Ltd | Real estate | 2006 |
| Office Ventures Limited | Construction | 2021 |
| Offwidth Games Ltd | Information & communication | 2021 |
| OH What a Difference a Dave Makes Ltd | Construction | 2025 |
| Olway Inn (PUB) Ltd | Hospitality | 2024 |
| Olway Investments | Professional & scientific | 2015 |
| Ontracks 2025 Limited | Professional & scientific | 2025 |
| Orchard Pharmaceuticals Limited | Professional & scientific | 2022 |
| Oyster Pools and Hot TUB Holdings Limited | Construction | 2020 |
| P&T Agri Services Ltd | Extraterritorial | 2021 |