| My Easy Accounts Limited | Professional & scientific | 2023 |
| My London Studio Ltd | Information & communication | 2025 |
| My Shopping Base Limited | Wholesale & retail | 2021 |
| My Tranquility Guard Ltd | Manufacturing | 2025 |
| Mydas Tech Ltd | Information & communication | 2022 |
| Mylands Limited | Wholesale & retail | 2000 |
| Mylen Limited | Education | 2024 |
| Mynisu Digitals Ltd | Information & communication | 2023 |
| N.B.Aldridge & SON Limited | | 1959 |
| N.J.S. Builders Limited | Construction | 2002 |
| N8SHOP Limited | Wholesale & retail | 2024 |
| Nabeeha(Uk) Ltd | Hospitality | 2018 |
| Naeem-Nimah Limited | Information & communication | 2024 |
| Nails and Spa Limited | Other services | 2010 |
| Naina H Kanji Limited | Professional & scientific | 2015 |
| Nash Audio | Information & communication | 2022 |
| National Stud Limited | Agriculture & fishing | 2007 |
| Naturemoor Limited | Transport & logistics | 1991 |
| Nature’S Little Gifts Ltd | Wholesale & retail | 2023 |
| NB Civil Engineering Ltd | Construction | 2019 |
| NBG Services Ltd | Construction | 2023 |
| NC Hockey Ltd | Education | 2024 |
| Ndipnoh Malayena Jeftleomane Limited | Wholesale & retail | 2025 |
| Ndlovu Group Ltd | Construction | 2023 |
| NDN Transport Ltd | Transport & logistics | 2016 |
| NEA Property Services Ltd | Construction | 2007 |
| Nedging 2008 Limited | Extraterritorial | 2003 |
| Nedging Hall Estate Limited | Manufacturing | 2000 |
| Nerylo Ltd | Real estate | 2023 |
| Nessling & Nessling Ltd | Arts & recreation | 2022 |
| Netlaw INT LLP | | 2019 |
| Neurophonics Ltd | Information & communication | 2022 |
| Neurosci Consulting Ltd | Professional & scientific | 2023 |
| New Beginnings Florist Limited | Wholesale & retail | 2003 |
| New Star Boom Limited | Wholesale & retail | 2025 |
| New-Tech Farm Developments Limited | Manufacturing | 1986 |
| Newdawn (Anglia) Limited | | 1993 |
| Newmarket & Suffolk Real Tennis Limited | Arts & recreation | 1998 |
| Newmarket Paint Company Limited | Manufacturing | 2001 |
| Newmarket Plant Hire Limited | Administrative & support | 1987 |
| Newmarket Sports and Leisurewear Limited | Wholesale & retail | 1976 |
| Newton Green Golf Club Limited | Arts & recreation | 2016 |
| Nexado Digital Ltd | Information & communication | 2025 |
| Nexgen Commerce Group Ltd | Wholesale & retail | 2017 |
| Next Gates Education Ltd | Education | 2023 |
| Next Home Properties Ltd | Real estate | 2020 |
| Nick Buxton QS Services Limited | Professional & scientific | 2019 |
| Nick Pyett Limited | Information & communication | 2014 |
| Nicp Ltd | Real estate | 2023 |
| Nigeria ALL Stars Sports Club Ltd | Arts & recreation | 2023 |
| Nimibest Ltd | Health & social care | 2023 |
| Nimo Int’L Co., Limited | Extraterritorial | 2015 |
| Nimrata Consulting Limited | Administrative & support | 2018 |
| Ninagear Limited | | 1984 |
| Nineteenfiftythree Ltd | Real estate | 2022 |
| Ningbo Distart Craft Co., Ltd. | Extraterritorial | 2013 |
| Nixis Limited | Extraterritorial | 1999 |
| NLM Trade Ltd | Wholesale & retail | 2024 |
| NO One’S Skin London Ltd | Professional & scientific | 2021 |
| NO Play Ltd | Arts & recreation | 2022 |
| Noble Guidance Limited | Education | 2025 |
| Nolan Select Ltd | Other services | 2024 |
| Nomadic Routes Ltd | Wholesale & retail | 2026 |
| Norfolk & Suffolk General Trading Company Limited | Real estate | 1983 |
| North Star South Limited | Transport & logistics | 1948 |
| North West One Management Limited | Construction | 1974 |
| Northpoint Commerce Ltd | Wholesale & retail | 2022 |
| Norton Peskett (Services) Limited | Extraterritorial | 1995 |
| Novateur International Group Ltd | Wholesale & retail | 2021 |
| NS Onehundredandtwelve Ltd | Wholesale & retail | 2025 |
| NTA Management Ltd | Professional & scientific | 2006 |
| Nursey & SON Limited | Real estate | 1957 |
| Nushi Limited | Information & communication | 2023 |
| NYO Tech Services Ltd | Information & communication | 2021 |
| Nyvas Oceanic Resources Limited | Transport & logistics | 2025 |
| O.& C.Butcher(Outfitters)Limited | Wholesale & retail | 1952 |
| Obsinex Ltd | Information & communication | 2025 |
| Ocean Amusements Limited | Arts & recreation | 1966 |
| OFF the Wall Pictures Limited | Administrative & support | 1989 |
| OJB Properties Ltd | Real estate | 2023 |
| Old Buckenham Hall(Brettenham)Educational Trust Limited | Education | 1967 |
| Old Foundry Place Management Company Limited | Real estate | 1987 |
| Olenko Ltd | Administrative & support | 2022 |
| Oliver T. Properties Limited | Real estate | 1990 |
| Olut Limited | | 1971 |
| OM Accountancy Ltd | Education | 2022 |
| Omax Ltd | Wholesale & retail | 2015 |
| ON the Flawdrobe Ltd | Wholesale & retail | 2019 |
| One EYE Beauty Ltd | Wholesale & retail | 2023 |
| Onefifty Ltd | Information & communication | 2014 |
| Oollaa Ltd | Wholesale & retail | 2021 |
| Opal Travels and Consulting Ltd | Administrative & support | 2024 |
| Opcao Ltd | Manufacturing | 2024 |
| Open Access Foundation | Information & communication | 2023 |
| Orbitglowcraft Ltd | Wholesale & retail | 2025 |
| ORC Investments Ltd | Wholesale & retail | 2022 |
| Orwell Mencap | Health & social care | 2006 |
| Orwell Professional Decorators Ltd | Construction | 2007 |
| Ostarven Limited | Wholesale & retail | 1978 |
| OUR Touch Limited | Administrative & support | 2007 |