| MGK Carpentry & Construction Limited | Construction | 2025 |
| Micro-Precision Instruments Limited | Real estate | 1944 |
| Midda Martial Arts Ltd | Other services | 2019 |
| Midwest Publications Limited | Information & communication | 2004 |
| Milfsport Limited | Arts & recreation | 2012 |
| Milk Diamonds Ltd | Manufacturing | 2019 |
| Mill Lane Beckington Management Company Limited | Households | 2017 |
| Mill on the Brue Limited | Education | 2000 |
| Millers Electrical Contractors Limited | Construction | 2011 |
| Millers Homewares Ltd | Wholesale & retail | 2024 |
| Millie Moon Ltd | Wholesale & retail | 2005 |
| Milsom Metalworks Ltd | Manufacturing | 2024 |
| MIM Integration Limited | Administrative & support | 2024 |
| Mirage Inks Limited | Manufacturing | 1983 |
| Mission Control Limited | Administrative & support | 2011 |
| Mistover Limited | Professional & scientific | 2002 |
| MJS Surfacing Ltd | Construction | 2017 |
| MK Oriental Limited | Hospitality | 2022 |
| Mkcm Property Ltd | Real estate | 2021 |
| MKR Construction Projects Ltd | Construction | 2004 |
| ML Auto Tech Services Ltd | Wholesale & retail | 2019 |
| Mmig UK Ltd | Professional & scientific | 2023 |
| Mncg Ltd | Professional & scientific | 2018 |
| Mobile Mechanic Services Limited | Wholesale & retail | 2002 |
| Mobility Scooters 2 YOU Ltd | Administrative & support | 2019 |
| Model ME This Limited | Information & communication | 2020 |
| Momo Promo Ltd | Arts & recreation | 2024 |
| Monarch Joinery Frome Ltd | Manufacturing | 2020 |
| Monchique Investments Limited | Real estate | 2003 |
| Monet Investments Limited | Real estate | 2001 |
| Monika Subrt Consultancy Ltd | Information & communication | 2018 |
| Monkley Consulting Limited | Professional & scientific | 2025 |
| MOO2.ME Limited | Wholesale & retail | 2024 |
| Moore & Moore Technology Ltd | Professional & scientific | 2023 |
| Moore 4 Mortgages Ltd | Financial services | 2015 |
| Motorhome Hire Adventure Ltd | Administrative & support | 2020 |
| Motorworks Freehold Ltd | Real estate | 2025 |
| Motorworks Frome Ltd | Construction | 2019 |
| Motte and Bailey Limited | Professional & scientific | 2010 |
| Mount Art Services Ltd | Manufacturing | 2015 |
| Mountree Limited | Real estate | 2018 |
| MRE Highways Services Limited | Administrative & support | 2015 |
| Mrock Ltd | Construction | 2019 |
| Mugmatters Limited | Manufacturing | 2004 |
| Mums Shapewear Limited | Wholesale & retail | 2021 |
| Murcia Property Developments Ltd | Professional & scientific | 2005 |
| MW Martial Arts Ltd | Arts & recreation | 2025 |
| My Boutique Stay Limited | Hospitality | 2021 |
| My Five Properties Ltd | Real estate | 2024 |
| Mycelium Collective C.I.C. | Education | 2024 |
| Mythe Systems Limited | Mining & quarrying | 2012 |
| N Green Energy Ltd | Professional & scientific | 2024 |
| N K Hoses Limited | Manufacturing | 2011 |
| N.B. Avis Ltd | Construction | 1997 |
| Naolight Ltd | Arts & recreation | 2019 |
| Natural Frameworks Ltd | Construction | 2019 |
| NBG Translation & Linguistic Services Ltd | Professional & scientific | 2021 |
| Ncla Consult Limited | Professional & scientific | 2026 |
| NCREA8TIVE Ltd | Manufacturing | 2021 |
| Ndrwdnhm Ltd | Manufacturing | 2022 |
| Nearly New Store Limited | Wholesale & retail | 2023 |
| Neat Heat Fuel Ltd | Wholesale & retail | 2019 |
| Neate Carpentry Limited | Construction | 2012 |
| Neighbourhood Toolbox CIC | Professional & scientific | 2024 |
| Neil Brant Consulting Ltd | Professional & scientific | 2018 |
| Nerate Ltd | Information & communication | 2025 |
| Netitude Group Limited | Information & communication | 2021 |
| Netitude Limited | Information & communication | 2009 |
| Network for Practices Ltd | Education | 2007 |
| Neuron Creative Ltd | Information & communication | 2014 |
| New Approach Developments Ltd | Construction | 2024 |
| New Old Friends Ltd. | Arts & recreation | 2012 |
| New Renaissance Temple CIC | Hospitality | 2024 |
| New Romantic Ltd | Wholesale & retail | 2023 |
| Newtown Chapel Management Company Limited | Real estate | 2005 |
| Nextwaveweb Ltd | Information & communication | 2026 |
| NIC Mulvaney Ltd | Professional & scientific | 2013 |
| Nicholls & Sons Ltd | Transport & logistics | 2018 |
| Nicholls Estates Ltd | Agriculture & fishing | 2023 |
| Nipper Nappies Limited | Wholesale & retail | 2020 |
| NIX Nought Nothing Ltd | Information & communication | 2006 |
| Nixon Kitchener Architects Ltd | Professional & scientific | 2024 |
| Noisy Little Monkey Limited | Information & communication | 2009 |
| Nomad Live Ltd | Arts & recreation | 2021 |
| Non-Toxic Masculinity Limited | Wholesale & retail | 2023 |
| North Mill Avoncliff Limited | Extraterritorial | 2009 |
| North London Builders Ltd | Construction | 2012 |
| Northan Limited | Wholesale & retail | 2017 |
| Northbank Property Partnership Ltd | Real estate | 2021 |
| Northend House (Frome) Management Company Limited | Households | 2024 |
| Northern JFS Limited | Hospitality | 2013 |
| Northumberland Properties (Bath)Limited | Real estate | 1961 |
| Noughts & Ones Ltd | Information & communication | 2017 |
| Nouveau Catering Ltd. | Hospitality | 2015 |
| Nova Sports and Coaching C.I.C. | Arts & recreation | 2017 |
| NSD Consultancy Ltd | Professional & scientific | 2011 |
| Nugent Vallis Brierley Limited | Professional & scientific | 1990 |
| Number 2 1835 Limited | Real estate | 2020 |
| Nunney Coaching Inn Ltd | Hospitality | 2018 |
| NWM Contracts Limited | Wholesale & retail | 2014 |