| Meadside Developments Limited | Construction | 2007 |
| Meiji Techno UK Limited | Wholesale & retail | 1997 |
| Mendip Heating & Plumbing Services Ltd | Construction | 2006 |
| Mendip Hills Mineral Water Limited | Manufacturing | 2004 |
| Mendip Hills Spring Water Limited | Manufacturing | 2004 |
| Mendip Land Surveys Limited | Professional & scientific | 2002 |
| Mercia Care Homes (Holdings) Limited | Professional & scientific | 2003 |
| Mercia Care Homes Limited | Health & social care | 2003 |
| Merriway Limited | Extraterritorial | 1983 |
| Merry Property Limited | Households | 2020 |
| Messagepoint Limited | Information & communication | 1999 |
| Metrics Engineering Co Limited | Manufacturing | 1983 |
| Metrics Engineering Holding Company Limited | Administrative & support | 2006 |
| MGC Holdings Limited | Wholesale & retail | 1988 |
| Miah's Woodcock Limited | Hospitality | 2018 |
| Michael Burdge Limited | Wholesale & retail | 1996 |
| Microfarm Limited | Information & communication | 2006 |
| Middle Touches Management Company Limited | Households | 1982 |
| Middlecombe Nurseries Limited | Hospitality | 1959 |
| Middleway Court Management Company Limited | Households | 1978 |
| Mike Ball Surfacing Limited | Construction | 1997 |
| Millfield | Education | 1953 |
| Millfield School Enterprises Limited | Wholesale & retail | 1981 |
| Milton Court Management Limited | Households | 1987 |
| Miltons Estate Limited | Agriculture & fishing | 1997 |
| Minehead MOT Centre Limited | Wholesale & retail | 2003 |
| MKT Bygmester Limited | Agriculture & fishing | 2007 |
| Mo's Aunt Limited | Information & communication | 2004 |
| Monaghan Mushrooms Limited | Manufacturing | 2003 |
| Monkay Limited | Information & communication | 2006 |
| Montigo Resorts (UK) Limited | Hospitality | 2023 |
| Moor Park (North Somerset) Limited | Other services | 1994 |
| Moorlands Court Management Limited | Professional & scientific | 1994 |
| Morellis Limited | Real estate | 1957 |
| Moulderz Property Ltd | Real estate | 2017 |
| Mountbatten Nursing Home Limited | Health & social care | 2001 |
| MRG, EJ, JRM & CC Scott Limited | Agriculture & fishing | 2005 |
| Mulberry (UK) Limited | Professional & scientific | 1999 |
| Mulberry Company (Design) Limited | Manufacturing | 1985 |
| Mulberry Company (Europe) Limited | Professional & scientific | 1989 |
| Mulberry Company (Holdings) Limited | Professional & scientific | 1994 |
| Mulberry Company (Sales) Limited | Wholesale & retail | 1980 |
| Mulberry Company (Shoes) Limited | Professional & scientific | 1982 |
| Mulberry Fashions Limited | Professional & scientific | 1994 |
| Mulberry Group PLC | Professional & scientific | 1974 |
| Mulberry Leathers Limited | Professional & scientific | 1994 |
| N & J Carpentry Limited | Construction | 2003 |
| N & P Auto Repairs Ltd | Wholesale & retail | 1999 |
| N R Bishop Electrical Contractor Limited | Construction | 2003 |
| N S Glazing Limited | Construction | 2003 |
| N. a. George Limited | Transport & logistics | 2003 |
| N.C. Flooring Limited | Construction | 2003 |
| N.H. Case Limited | Wholesale & retail | 1985 |
| Natajak Limited | Real estate | 1998 |
| Natasha Jane Ltd | Manufacturing | 2013 |
| Nazca Systems Limited | Professional & scientific | 2001 |
| Nazli Ltd | Hospitality | 2022 |
| NBA Solutions Limited | Professional & scientific | 2003 |
| Ncom Ltd | Information & communication | 2007 |
| NET Zero Five Properties Limited | Real estate | 2001 |
| Netherlands Andrew International Chemical Co., Limited | Extraterritorial | 2023 |
| Newham Land and Build Limited | Construction | 2004 |
| Nicholas Wylde (Goldsmith) Limited | Wholesale & retail | 1990 |
| Nick Brooks Installation & Maintenance Limited | Construction | 2005 |
| Nigel Dorothy Limited | Construction | 2003 |
| Nine Montpelier Management Limited | Hospitality | 1978 |
| NO Monkey Business Consultancy Limited | Extraterritorial | 2006 |
| NO.53 the Salon Ltd | Other services | 2004 |
| Noble Solutions Limited | Professional & scientific | 1997 |
| Norset Office Supplies Limited | Wholesale & retail | 1990 |
| Northay Farms Limited | Agriculture & fishing | 1958 |
| Norway Ogarsen International Biotechnology Co., Limited | Extraterritorial | 2023 |
| NP Fuel & Shop Ltd | Wholesale & retail | 2026 |
| Number 9 Summerlands (Management) Company Limited | Real estate | 1999 |
| Nutwell Saddlery Limited | Wholesale & retail | 2005 |
| O.G.T. Forensic Limited | Professional & scientific | 2001 |
| Oaktower Properties Limited | Real estate | 2003 |
| Octagon Heating Services Ltd. | Construction | 1996 |
| Old Byres Limited | Hospitality | 2017 |
| Olive Grove Catering Limited | Hospitality | 2005 |
| Olumax Services Ltd | Health & social care | 2025 |
| Omni Direct Ltd | Transport & logistics | 2017 |
| OPH Original Limited | Professional & scientific | 2001 |
| Optin Ltd | Financial services | 2010 |
| Organic Power Corporation Limited | Professional & scientific | 2001 |
| Organic Power North West Limited | Professional & scientific | 2003 |
| Organic Power NRG Limited | Professional & scientific | 2007 |
| Organic Power South West Ltd | Professional & scientific | 2002 |
| Organic Power Wales Limited | Professional & scientific | 2003 |
| Organic Wastes Management Limited | Water & waste | 2006 |
| Orion Photonics Ltd | Manufacturing | 2011 |
| Ornitrex Ltd | Hospitality | 2006 |
| Orphfund Limited | Education | 2005 |
| Oscar Fish Bar Limited | Hospitality | 2019 |
| OTF Facilities Management Limited | Construction | 2000 |
| OTP Clothing Ltd | Wholesale & retail | 2024 |
| OUT of Hours Typing Limited | Administrative & support | 2006 |
| OVA Imports Ltd | Extraterritorial | 2023 |
| Oval (259) Limited | Financial services | 1986 |
| Over the Water Translations Ltd | Professional & scientific | 2015 |