| Motidration Ltd | Wholesale & retail | 2023 |
| Motion Alley Ltd | Information & communication | 2013 |
| Motorbike Finder Limited | Information & communication | 2002 |
| Motorhome Finder Ltd | Extraterritorial | 2006 |
| Motorsport Catering Limited | Hospitality | 2025 |
| Motorsport Club of Chelmsford Limited | Arts & recreation | 1982 |
| Motorworx Ipswich Ltd | Wholesale & retail | 2025 |
| Mousemat Design Limited | Arts & recreation | 2001 |
| Moxster Productions Ltd | Information & communication | 2016 |
| MPA Motor Engineering Limited | Wholesale & retail | 2014 |
| MPM Hire Ltd | Transport & logistics | 2019 |
| MR Shifter Ipswich Ltd | Transport & logistics | 2021 |
| MR Tech OPS Limited | Information & communication | 2023 |
| MR6X9DESIGN Ltd | Arts & recreation | 2022 |
| Mudroomsuk Ltd | Other services | 2024 |
| Mujada Games Ltd | Information & communication | 2025 |
| Mullins Dowse Architects Limited | Professional & scientific | 2011 |
| Multi Creative Media Ltd | Information & communication | 2015 |
| Musical Tales Ltd | Manufacturing | 2001 |
| My Little World Ltd | Manufacturing | 2017 |
| My Orchard Limited | Wholesale & retail | 2025 |
| My Tenancy Clean Group Ltd | Administrative & support | 2026 |
| My Tenancy Cleans Ltd | Administrative & support | 2025 |
| Myson Management Limited | Real estate | 2010 |
| N G a Connect Limited | Information & communication | 2011 |
| Nairda Ltd | Health & social care | 2023 |
| Nanpeidai Square Limited | Financial services | 2022 |
| Nash Auto Ltd. | Transport & logistics | 2024 |
| National Disability Card Ltd | Other services | 2019 |
| National Youth String Orchestra | Arts & recreation | 2005 |
| Native Gardens & Forestry Limited | Agriculture & fishing | 2011 |
| Native Yarns Limited | Wholesale & retail | 2014 |
| Naunton Properties Limited | Real estate | 2017 |
| NB Recruitment Solutions Ltd | Professional & scientific | 2013 |
| Nelson Potter Limited | Manufacturing | 1986 |
| Nesling Enterprises Limited | Agriculture & fishing | 2026 |
| Nest Construction Corporation Limited | Construction | 2019 |
| Nest Development Corporation Limited | Construction | 2010 |
| Netradial Ltd | Manufacturing | 2013 |
| Neuroedge Growth Limited | Administrative & support | 2025 |
| Neville Stein Associates Ltd | Professional & scientific | 2026 |
| New Look Carpentry and Maintenance Ltd | Construction | 2020 |
| New Quay Terrace Management Company Limited | Households | 2010 |
| New Stowe Developments Limited | Construction | 2017 |
| New Street Market Ltd | Hospitality | 2025 |
| New Street Projects Holdings Ltd | Financial services | 2026 |
| New Street Studio Woodbridge Ltd | Wholesale & retail | 2026 |
| New Street Woodbridge Ltd | Real estate | 2021 |
| Newbourne Campers Limited | Wholesale & retail | 2020 |
| Newbourne Farm Shop Ltd | Agriculture & fishing | 2014 |
| Newbourne Kitchen Limited | Hospitality | 2026 |
| Newday Design Ltd | Real estate | 2023 |
| Newleaf Creative Ltd | Professional & scientific | 2018 |
| Niche Cocktails Ltd | Hospitality | 2013 |
| Nicholas Shaw Fine Art Ltd | Wholesale & retail | 2024 |
| Nick Brown Transport Ltd. | Transport & logistics | 2001 |
| Nightingale Estate Management Ltd | Real estate | 2018 |
| Nightingale Place (Woodbridge) Property Management Company Limited | Construction | 2011 |
| NJW Consulting Limited | Professional & scientific | 2023 |
| NO Extra Source Limited | Information & communication | 2023 |
| NO10 Beauty & Aesthetics Ltd | Other services | 2025 |
| Noble Rebels Limited | Professional & scientific | 2014 |
| Noblecastle Limited | Agriculture & fishing | 1984 |
| Noise of Art Ltd | Information & communication | 2006 |
| Nomad Ventures GB CIC | Professional & scientific | 2019 |
| Noodle Express Holdings Limited | Hospitality | 2017 |
| Noon Seven Limited | Real estate | 2016 |
| Nordbalt Ltd | Wholesale & retail | 2024 |
| Norfolk Sameday Couriers Ltd | Transport & logistics | 2024 |
| North & Partners Limited | Administrative & support | 2020 |
| North & South Independent Agronomy Ltd | Professional & scientific | 2015 |
| North & South Travel Limited | Administrative & support | 2019 |
| Northland (Reydon) Ltd | Construction | 2017 |
| Norton Taylor Nunn Ltd | Construction | 2018 |
| Notcutts Group Limited | Wholesale & retail | 2011 |
| Nourish Suffolk Ltd | Hospitality | 2021 |
| Nowselect Limited | Wholesale & retail | 1987 |
| Nu-Life Furnishings Ltd | Other services | 2016 |
| Number Nine Sports Medicine and Performance Ltd | Health & social care | 2022 |
| Numbers Accountancy Ltd | Professional & scientific | 2016 |
| Nura Fit Ltd | Information & communication | 2026 |
| Nureau Wocket Solutions Limited | Information & communication | 2007 |
| Nxcxi Ltd | Extraterritorial | 2024 |
| Oakbridge Global Limited | Professional & scientific | 2021 |
| Oaklands Construction Suffolk Ltd | Construction | 2023 |
| Oasis Property Limited | Real estate | 2016 |
| Oates Property Management Ltd | Agriculture & fishing | 2024 |
| Ocean PR Ltd | Professional & scientific | 2018 |
| Oddsoft Limited | Information & communication | 1996 |
| Odyssey Film Productions Ltd | Information & communication | 2026 |
| Offerwide Holdings Ltd | Financial services | 2023 |
| Offerwide Limited | Wholesale & retail | 1990 |
| Offset Films Limited | Information & communication | 2015 |
| Oftec Insurance Services Limited | Information & communication | 2010 |
| Oftec Limited | Professional & scientific | 1992 |
| Oftec Warranty Limited | Administrative & support | 2016 |
| Ogden Planning Limited | Professional & scientific | 2025 |
| OIL Firing Technical Association Limited | Professional & scientific | 2013 |
| Oilsave Limited | Manufacturing | 2013 |
| Oiltech Heating Ltd | Construction | 2011 |