| M K Animal Healthcare Limited | Professional & scientific | 2017 |
| M&M Hotel (Penrith) Limited | Hospitality | 2025 |
| M&M Motor Engineers Ltd | Wholesale & retail | 2021 |
| M121 Associates Ltd | Professional & scientific | 2023 |
| M6 Diesel Services Limited | Wholesale & retail | 1976 |
| Mace & Mills Limited | Hospitality | 2025 |
| Mace Property Developments Ltd | Extraterritorial | 2023 |
| Mackey Surgery Limited | Health & social care | 2015 |
| Made by US Limited | Extraterritorial | 2007 |
| MAE Facility Management Ltd | Construction | 2022 |
| Maghreb Services Ltd | Professional & scientific | 2008 |
| Mains Farm Caravan & Campsite Limited | Hospitality | 2021 |
| Mains Farm Events Limited | Hospitality | 2021 |
| MAK LLC Ltd | Wholesale & retail | 2020 |
| Mallaband Legal Limited | Professional & scientific | 2021 |
| Mallett Design Ltd | Construction | 2014 |
| Mallett Developments Ltd | Construction | 2022 |
| Mallett Holdings Limited | Financial services | 2018 |
| Malmon Property Company Limited | Real estate | 1960 |
| Mamu Global Ltd | Real estate | 2024 |
| Mandale Developments Limited | Construction | 2002 |
| Mango Rigging and Rope Limited | Administrative & support | 2010 |
| Manhattans (Barrow) Limited | Hospitality | 2013 |
| Manor Farm Management Company Crofton Ltd | Households | 2024 |
| Manor Furniture Ltd | Wholesale & retail | 2012 |
| Manor House Garage Limited | Wholesale & retail | 2002 |
| Manor of Orton CIC | Real estate | 2023 |
| MAP of AG Solutions Limited | Agriculture & fishing | 2006 |
| MAP of Agriculture Group Ltd. | Information & communication | 2015 |
| MAP of Agriculture Ltd. | Information & communication | 2015 |
| Maple Bridge Corporation Limited | Hospitality | 2011 |
| Mardale Training Ltd | Information & communication | 2026 |
| Marian Park Limited | Construction | 2022 |
| Marilyn's (Barrow) Limited | Hospitality | 2015 |
| Marinedash Ltd | Information & communication | 2020 |
| Mark Beach Forestry Sales Limited | Wholesale & retail | 2019 |
| Mark Cameron Training Limited | Information & communication | 2013 |
| Mark Holding Mitsuru Karate Ltd | Arts & recreation | 2014 |
| Mark Peplow Limited | Information & communication | 2012 |
| Marshall & Fowler Properties Limited | Real estate | 2016 |
| Martin B Squires Limited | Professional & scientific | 2012 |
| Martin Hall Freelance FD Limited | Professional & scientific | 2018 |
| Martin Price Consulting Limited | Professional & scientific | 2009 |
| Martin Smith Contracts Limited | Construction | 2015 |
| Martlew & Costello Ltd | Wholesale & retail | 2020 |
| Marvellous Entertainment Limited | Hospitality | 2025 |
| Mason BEE Installations Limited | Construction | 2016 |
| Matrix Traffic and Transport Data Limited | Administrative & support | 2016 |
| Matsurf Ltd | Professional & scientific | 2017 |
| Maurice Barnes Racing Ltd | Arts & recreation | 2017 |
| MAX Dunford Farming Limited | Agriculture & fishing | 2023 |
| MBE Eden Services Limited | Construction | 2025 |
| MC Events Ltd | Administrative & support | 2021 |
| MC Ferguson (Interiors) Limited | Wholesale & retail | 2015 |
| Mckenzie Morris Limited | Extraterritorial | 2014 |
| Mcmullen Property Developments Limited | Real estate | 2021 |
| Mcmw Solutions Limited | Construction | 2014 |
| Mcphee's Goat Company Ltd | Agriculture & fishing | 2019 |
| MD Parcels Ltd | Other services | 2025 |
| Meaburn Hall Ltd | Agriculture & fishing | 2025 |
| Meadow Rigg (Burneside Road) Limited | Construction | 2021 |
| Meadow Rigg (Kendal) Management Company Limited | Real estate | 2022 |
| Meadows Accountancy Ltd | Professional & scientific | 2022 |
| Mean Old Scene Ltd | Wholesale & retail | 2021 |
| Medical Spa Partners C.I.C. | Health & social care | 2019 |
| Mediprof Ltd | Real estate | 2013 |
| Mell Fell Regen Ltd | Agriculture & fishing | 2023 |
| Merchant Associates Ltd | Administrative & support | 2025 |
| Mere Commercial Limited | Real estate | 2015 |
| Mereside Property Management Ltd | Real estate | 2014 |
| Messrs Allen | | 1999 |
| Messrs Atkinson | Administrative & support | 2012 |
| Messrs Dalton Limited | Real estate | 2021 |
| Messrs Grierson | Administrative & support | 2008 |
| MET Property Services Ltd | Hospitality | 2021 |
| Metcalfe Plant Hire Limited | Construction | 1987 |
| Metrix Analytics Ltd | Information & communication | 2025 |
| Mhrj Consulting Ltd | Construction | 2026 |
| Miami Sun Penrith Ltd | Other services | 2022 |
| Middlegate Kebab Ltd | Hospitality | 2025 |
| Mike Dixon Motors Ltd | Wholesale & retail | 2023 |
| Mike Dixon Prestige Cars Ltd | Wholesale & retail | 2025 |
| Mike Hare Joinery & Maintenance Limited | Construction | 2013 |
| Mike Keast Technology Limited | Professional & scientific | 2018 |
| Milburn Developments (UK) Limited | Construction | 2025 |
| Milburn Farms Limited | Agriculture & fishing | 2020 |
| Millard Homes Ltd | Real estate | 2003 |
| Millener Group Limited | Households | 2026 |
| Miller Home Improvements Ltd | Construction | 2023 |
| Mind & Matter Limited | Health & social care | 2024 |
| Mind Flow International Ltd | Information & communication | 2021 |
| Mindfulmart Ltd | Wholesale & retail | 2023 |
| Mindstreams Limited | Information & communication | 2016 |
| Ming's Kitchen Ltd | Hospitality | 2024 |
| Minh Lucky Properties Service Limited | Real estate | 2025 |
| Mini Market Penrith Ltd | Wholesale & retail | 2023 |
| MJ Kilcoyne Ltd | Health & social care | 2018 |
| Mkdombrowsky Limited | Health & social care | 2023 |
| Mlad Ltd | Health & social care | 2011 |
| Mmnh Holdings Ltd | Mining & quarrying | 2024 |