| M&L Decor Ltd | Construction | 2025 |
| Mahnat Ltd | Wholesale & retail | 2026 |
| Malawi Cane Furniture UK Limited | Wholesale & retail | 2018 |
| MAN2AUTOMOTIVE Limited | Wholesale & retail | 2013 |
| Management & Capital Gain Group Ltd | Professional & scientific | 2007 |
| Mantel Equestrian Ltd | Agriculture & fishing | 2024 |
| Marigold Rentals Ltd | Real estate | 2024 |
| Mario Courier Ltd | Transport & logistics | 2019 |
| Mark Whatley Ltd | Real estate | 2012 |
| Markwick Consulting Limited | Professional & scientific | 2019 |
| Masons Trees and Woodland Management Limited | Other services | 2017 |
| Matt Swann Creative Limited | Arts & recreation | 2010 |
| Maud Ltd | Public administration | 2023 |
| Mavrec Ltd | Administrative & support | 2023 |
| MAX Oliver Developments Ltd | Financial services | 2010 |
| MB Golf Marketing Limited | Manufacturing | 2020 |
| MD Property Management (Hampshire) Ltd | Real estate | 2014 |
| Meals With MAX Ltd | Information & communication | 2024 |
| Mele Cooke Ltd | Real estate | 2024 |
| Meltex Textiles Limited | Wholesale & retail | 2023 |
| MEM Barbers Limited | Other services | 2024 |
| Mendem Motors Limited | Wholesale & retail | 2003 |
| Metallogic Solutions Ltd | Professional & scientific | 2026 |
| Metrix Electronics Limited | Manufacturing | 1999 |
| MG Retail Consulting Limited | Professional & scientific | 2012 |
| Michael Dales Roofing Ltd | Construction | 2026 |
| MID Suffolk Business Park (EYE) Management Company Limited | Real estate | 2000 |
| Mihai Craciun Ltd | Professional & scientific | 2024 |
| Mike Jones Accounting Ltd | Professional & scientific | 2020 |
| Millersql Ltd | Information & communication | 2015 |
| Milo Financial Ltd | Financial services | 2012 |
| Mim’S Whimsies Ltd | Wholesale & retail | 2024 |
| Mindscape Consulting Limited | Professional & scientific | 2004 |
| Mindstream Solutions Ltd | Information & communication | 2025 |
| Mint Face | Arts & recreation | 2019 |
| Mitra Digital Ltd | Professional & scientific | 2018 |
| Mitzi & Theobald Ltd | Wholesale & retail | 2026 |
| Mjagoda Ltd | Transport & logistics | 2026 |
| MJP Fuel Solutions Ltd | Professional & scientific | 2026 |
| Mkmetals Ltd | Construction | 2024 |
| MO & J Auto Ltd | Wholesale & retail | 2025 |
| Mobile Motorglass Ltd | Manufacturing | 2006 |
| Mobility Measure Ltd | Information & communication | 2023 |
| Modernized Property Ltd | Real estate | 2023 |
| Montague Homes Limited | Construction | 2016 |
| Montague Property Services Ltd | Real estate | 2016 |
| Mortimer Gardens (Tadley) Management Company Limited | Households | 1994 |
| Mortons Travel Limited | Transport & logistics | 2012 |
| Mother and Midwife Limited | Education | 2021 |
| Motoselect Ltd | Wholesale & retail | 2021 |
| Movement Media Limited | Information & communication | 2018 |
| MRM Reading Limited | Manufacturing | 2025 |
| MSE Heat & Plumb Ltd | Construction | 2026 |
| MSP365 Ltd | Real estate | 2025 |
| Mulberry Heath Ltd | Professional & scientific | 2013 |
| Mulberry Hill Consulting Ltd | Information & communication | 2025 |
| Munn Connect Ltd | Information & communication | 2026 |
| MWG Consult Limited | Professional & scientific | 2026 |
| Nash Court Management Tadley Limited | Households | 1999 |
| Nashco Holdings Ltd | Financial services | 2023 |
| NAT Trade Ltd | Wholesale & retail | 2026 |
| Nathan Barris Limited | Education | 2017 |
| National Construction Consultancy Ltd | Construction | 2018 |
| Navisharp Limited | Professional & scientific | 2025 |
| NB Project Engineering Ltd | Information & communication | 2011 |
| NET Zero Marketplace Ltd | Wholesale & retail | 2023 |
| New World Insight Limited | Information & communication | 2016 |
| Newar Limited | Arts & recreation | 2010 |
| Newlook Auto Design Ltd | Wholesale & retail | 2019 |
| Newnham Flow Solutions Ltd | Professional & scientific | 2025 |
| Next Generative AI Limited | Information & communication | 2025 |
| Nibbles Catering & Events Limited | Hospitality | 2018 |
| Nicknaq Limited | Professional & scientific | 2014 |
| Nicole Mae's Bridal Ltd | Wholesale & retail | 2022 |
| Nineteen Ninety Three Ltd | Information & communication | 2013 |
| NJM & Sons Rental Limited | Real estate | 2018 |
| NKA Tech Limited | Information & communication | 2016 |
| Nobody Special Limited | Manufacturing | 2024 |
| North Hants Property Rentals Ltd | Real estate | 2019 |
| Northbourne Practice Ltd | Health & social care | 2018 |
| Northcote Bespoke Limited | Construction | 2021 |
| NR 53 Ltd | Extraterritorial | 2014 |
| Nucleolus Ltd | Information & communication | 2016 |
| Nullpoint Limited | Information & communication | 2018 |
| Oak Bridge Developments Ltd | Construction | 2024 |
| Oakbee Limited | Real estate | 2020 |
| Oakley Road Management Company Limited | Households | 2002 |
| Oakley Windows Limited | Construction | 2008 |
| Oaktree Pubs Ltd | Hospitality | 2025 |
| OBL One Limited | Manufacturing | 2016 |
| Ochre Design & Artwork Ltd | Professional & scientific | 2014 |
| Oddities Ltd | Wholesale & retail | 2014 |
| Office Building Maintenance Ltd | Construction | 2022 |
| Office Building Services Ltd | Construction | 2016 |
| OH My Paint and Design Ltd | Construction | 2023 |
| Olive Tree Bespoke Joinery Ltd | Manufacturing | 2021 |
| One Sharp Company Ltd | Professional & scientific | 2025 |
| Optel Ltd | Information & communication | 2023 |
| Optimum Vision Clinics Limited | Wholesale & retail | 2022 |
| Oramo Ltd | Information & communication | 2025 |