| Mitey Limited | Administrative & support | 2012 |
| MJ Acoustics Ltd | Extraterritorial | 2005 |
| Mjbaynes Limited | Construction | 2016 |
| Mjeh Limited | Information & communication | 2025 |
| MJM Workforce Ltd | Construction | 2026 |
| MJS Contracting Services Ltd | Construction | 2018 |
| MJT Property Solutions Limited | Construction | 2026 |
| MKK Storage Ltd | Manufacturing | 2022 |
| Mkltd Limited | Financial services | 2019 |
| Mksv Transport Ltd | Transport & logistics | 2017 |
| MM2 Care Homes Ltd | Health & social care | 2020 |
| MM2 Holdings Ltd | Financial services | 2022 |
| MM2 Properties (Wisbech) Ltd | Financial services | 2022 |
| Mmmjk Ltd | Transport & logistics | 2024 |
| Mode Automatic Ltd | Manufacturing | 2025 |
| Molehill Data Services Ltd | Information & communication | 2026 |
| Momin's Kitchen Ltd | Hospitality | 2016 |
| Monaghan Consultants Limited | Manufacturing | 1997 |
| Moon & Evison Limited | Wholesale & retail | 1949 |
| Moor Housing Developments Limited | Construction | 2020 |
| Mortgageability Ltd | Financial services | 2017 |
| Motionvue Limited | Wholesale & retail | 2025 |
| Mottram & Sons (Farmers) Limited | Real estate | 1952 |
| Mozgovoi & Partners Consulting Ltd | Professional & scientific | 2026 |
| MP Audio Ltd | Arts & recreation | 2018 |
| MP Forestry Ltd | Agriculture & fishing | 2025 |
| MPH Consultants Limited | Construction | 2010 |
| MR Bromley's Limited | Manufacturing | 2017 |
| MR Shifter East Anglia Limited | Transport & logistics | 2017 |
| MR Winston Properties Limited | Real estate | 2024 |
| MRA Contract Services Limited | Administrative & support | 2015 |
| MRD Mechanical Services Ltd | Professional & scientific | 2026 |
| Msatransport Ltd | Transport & logistics | 2024 |
| Mslt Limited | Transport & logistics | 2024 |
| MSP6 Technology Ltd | Information & communication | 2022 |
| MSW Renovations Ltd | Construction | 2026 |
| Msya Holdings Limited | Administrative & support | 2018 |
| MT Construction & Groundworks Limited | Construction | 2013 |
| MTS Electrical and Mechanical Engineering Ltd | Professional & scientific | 2022 |
| Mulberry Holdings Thornham Ltd | Construction | 2019 |
| Multiflora Flowers Ltd | Agriculture & fishing | 2017 |
| Murrow AD Plant Ltd | Energy | 2011 |
| Museon Limited | Information & communication | 2025 |
| Mustang Transport Limited | Transport & logistics | 2022 |
| Mutubuki Healthcare Services Ltd | Health & social care | 2018 |
| My House Online Ltd | Real estate | 2016 |
| Mylex Building Contractors Limited | Construction | 2018 |
| Myriane Care Limited | Public administration | 2023 |
| N & P DIY Products Limited | Manufacturing | 2011 |
| N J Turner Ltd | Agriculture & fishing | 2013 |
| N Shorja Brickworking Limited | Construction | 2022 |
| NA Property Rentals Limited | Real estate | 2024 |
| Nacaa Decorating Ltd | Construction | 2017 |
| Narasin Properties Limited | Construction | 2025 |
| Nasion Properties Limited | Real estate | 2024 |
| Natbella Ltd | Wholesale & retail | 2024 |
| National Labour Services Ltd | Construction | 2026 |
| Nationwide Road Marking Limited | Construction | 2018 |
| Nationwide Screeds Limited | Construction | 2014 |
| Natural Born Bulldog Limited | Wholesale & retail | 2017 |
| Natural Born Bullys Bedding Co Ltd | Wholesale & retail | 2023 |
| Navigator Three Counties Limited | Construction | 2018 |
| NB Construction (Holdings) Ltd | Construction | 2017 |
| NB Construction (UK) Limited | Construction | 2006 |
| NBC Estates Limited | Real estate | 2020 |
| NBC Homes Ltd | Construction | 2017 |
| NBC Plant Ltd | Administrative & support | 2017 |
| Nedumgattu Limited | Health & social care | 2018 |
| Neil Elliott Ltd | Administrative & support | 2025 |
| Nematodes Direct Limited | Wholesale & retail | 2015 |
| Nene Advisory Limited | Professional & scientific | 2025 |
| Nene Financial Planning Ltd | Professional & scientific | 2022 |
| Nene Meadows Development Company Limited | Real estate | 2020 |
| Nene Milling Company Limited | Manufacturing | 2000 |
| Nene Podiatry Ltd | Health & social care | 2024 |
| Nene Shop Ltd | Wholesale & retail | 2024 |
| Neo-Rusts Ltd | Financial services | 2026 |
| Nerobuild Ltd | Construction | 2025 |
| NET Assessments Limited | Administrative & support | 2014 |
| Network Safety Services Limited | Construction | 2012 |
| New Drove Flats Limited | Households | 2017 |
| Newgate Courier Ltd | Transport & logistics | 2021 |
| Newgate Site Carpentry Limited | Construction | 2022 |
| Newling Fruitgrowers Limited | Agriculture & fishing | 2003 |
| Newtal Limited | Professional & scientific | 2013 |
| Nexolve Limited | Information & communication | 2026 |
| Nextgen Water Limited | Extraterritorial | 2023 |
| Nexus Cabling Ltd | Construction | 2023 |
| NGR Plumbing and Heating Specialists Limited | Construction | 2021 |
| NIA Auto Ltd | Wholesale & retail | 2025 |
| Nicki Sophie Howell Ltd | Extraterritorial | 2025 |
| Nicki Williamson Mental Health Ltd | Health & social care | 2019 |
| Nicole Sophia Arter Ltd | Health & social care | 2025 |
| Niepla Transport Ltd | Transport & logistics | 2015 |
| NIK Build Limited | Construction | 2018 |
| Nikel Trading Limited | Manufacturing | 2010 |
| Nikolche Transport Ltd | Transport & logistics | 2023 |
| Nine Lives Theatre Company Limited | Arts & recreation | 2015 |
| NL Property Developments Ltd | Real estate | 2025 |
| NLV Property Investments Ltd | Real estate | 2026 |