| M5 Angling Limited | Administrative & support | 2000 |
| MAC Construction & Engineering Ltd | Construction | 2022 |
| Mainboys Publishing Ltd | Information & communication | 2025 |
| Maisonelhoria Ltd | Wholesale & retail | 2017 |
| MAK TEN Services Ltd | Information & communication | 2024 |
| Marine Fabrication (SW) Limited | Manufacturing | 2015 |
| Marine Safety Ltd | Manufacturing | 2025 |
| Martin Holloway Limited | Other services | 2016 |
| Marun Construction Ltd | Construction | 2014 |
| Maverick Property Group Ltd | Real estate | 2025 |
| Meridian Research Ltd | Administrative & support | 2019 |
| Metageno UK Ltd | Education | 2026 |
| Mike Dunlop & SON Builders Limited | Construction | 2013 |
| Miles Consultants (Somerset) Limited | Professional & scientific | 2013 |
| Mindfulness Psychotherapy Ltd | Health & social care | 2023 |
| Mobile Welding Supplies Limited | Wholesale & retail | 2003 |
| Montrachet Developments Limited | Professional & scientific | 2007 |
| Moor Digital Consulting Limited | Information & communication | 2018 |
| Moorend Management Company Ltd | Households | 2019 |
| Morel Enterprises Ltd | Professional & scientific | 2018 |
| Morgan FOX Ltd | Construction | 2008 |
| Morgan Property Group South West Ltd | Real estate | 2022 |
| Morley House Somerton Ltd | Real estate | 2019 |
| Morris & Perry Limited | Manufacturing | 1962 |
| Mortons Developments Ltd | Construction | 2022 |
| Mowries Flats Limited | Extraterritorial | 1990 |
| MR Batteries Ltd | Manufacturing | 2020 |
| MR Pristine Clean Ltd | Administrative & support | 2026 |
| Mulberry Lane Property Management Limited | Households | 2020 |
| Multieng Solutions Limited | Administrative & support | 2007 |
| Murron Interior Design Ltd | Professional & scientific | 2018 |
| Music Skills Limited | Education | 2007 |
| Nabh Ltd | Wholesale & retail | 2024 |
| Natural Nets Ltd | Manufacturing | 2021 |
| Naydon Equestrian Limited | Arts & recreation | 2016 |
| Nbna Properties Ltd | Real estate | 2025 |
| Neopartners Limited | Professional & scientific | 2006 |
| New Dawn Climate Ltd | Professional & scientific | 2025 |
| New Forest HR Ltd | Administrative & support | 2015 |
| Nexus Control Systems Limited | Manufacturing | 2017 |
| Ngre Northwich Ltd | Real estate | 2019 |
| Nrtfm Ltd | Information & communication | 2015 |
| Nuffield Farming Scholarships Trust | Education | 2003 |
| Nutkins UK Ltd | Professional & scientific | 2017 |
| Nynehead Care Limited | Health & social care | 2000 |
| Nynehead Court Farm Limited | Real estate | 2019 |
| O W Building Services Limited | Construction | 2022 |
| O'Halleran Plumbing & Heating Limited | Construction | 2017 |
| Oaklands Nursery Limited | Wholesale & retail | 2003 |
| Oggy Oggy Taunton Limited | Hospitality | 2016 |
| Ohmwise Limited | Information & communication | 2019 |
| OM Plumbing SW Ltd | Construction | 2025 |
| ON TAP (South West) Limited | Water & waste | 1998 |
| ON TAP Holdings (South West) Limited | Financial services | 2023 |
| One Gloucester ROW Limited | Hospitality | 1999 |
| Onefathom Limited | Education | 2010 |
| Open Door Surveyors Ltd | Administrative & support | 2010 |
| OS Plumbing and Renovation Services Ltd | Construction | 2026 |
| Osbornes of Kingsdon Limited | Administrative & support | 2005 |
| Ottersbrook Limited | Professional & scientific | 2013 |
| Oubridge Associates Limited | Professional & scientific | 1984 |
| OZ Electrical Solutions Limited | Construction | 2025 |
| P & S Properties SW Limited | Construction | 2016 |
| P a Edgar Plumbing & Heating Ltd | Construction | 2019 |
| P C Electrics (SW) Limited | Construction | 2014 |
| P H Crown Limited | Households | 2012 |
| P6TEY Pubs Limited | Professional & scientific | 2020 |
| Paccom Limited | Information & communication | 2026 |
| Pack Masonry Ltd | Manufacturing | 2014 |
| Pandon Limited | Arts & recreation | 1997 |
| Parkway Brewing Company Ltd | Manufacturing | 2018 |
| Parsigns Limited | Manufacturing | 2019 |
| Parzival Partners Ltd | Professional & scientific | 2020 |
| Passfield Park Limited | Professional & scientific | 2002 |
| Paul Spencer Design & Carving Ltd | Construction | 2010 |
| Pawsability Trading Limited | Other services | 2024 |
| Pear Tree Hire (SW) Ltd | Administrative & support | 2023 |
| Peter Barratt Ltd | Professional & scientific | 2022 |
| Peter Rood and SON Limited | Agriculture & fishing | 1959 |
| Peter Tulk Construction Limited | Construction | 2004 |
| Pfairhurst Ltd | Construction | 2016 |
| Pink Paper Pineapple Holdings Ltd | Extraterritorial | 2022 |
| Pixel Mountain Ltd | Information & communication | 2019 |
| Pledger Developments Ltd | Construction | 2024 |
| Pmgates Ltd | Manufacturing | 2024 |
| Pntr SW Ltd | Construction | 2024 |
| PO4 Management Limited | Information & communication | 2013 |
| Polden Vale Sheepskin Co Ltd | Manufacturing | 2019 |
| Porter's Place Limited | Real estate | 2017 |
| Porthuish Management Company Limited | Households | 1989 |
| Powerful Solutions Limited | Professional & scientific | 2005 |
| Propel Education Ltd | Education | 2018 |
| Propinno Ltd | Construction | 2024 |
| Provia Ventures Ltd | Information & communication | 2025 |
| Pyxi Group Limited | Information & communication | 2010 |
| Q H Mews Limited | Construction | 2014 |
| Quality ISO Services Ltd | Administrative & support | 2010 |
| Quality LED Industries Ltd | Administrative & support | 2017 |
| Quarryman Close Management Company Limited | Households | 2015 |
| Quercus (UK) Limited | Construction | 2006 |