| Meetdoris Ltd | Information & communication | 2021 |
| Megga Transport Limited | Transport & logistics | 2016 |
| Meister Trans Ltd | Transport & logistics | 2022 |
| Mercury Freight Ltd | Transport & logistics | 2023 |
| Merlion Property Holdings Ltd | Real estate | 2021 |
| Metro Living Ltd | Real estate | 2025 |
| MI Retail Ltd | Wholesale & retail | 2021 |
| MIA Healthcare Limited | Health & social care | 2021 |
| Michael Express Ltd | Transport & logistics | 2023 |
| Micklegarth LLP | | 2011 |
| Mihail Transport Logistic Ltd | Transport & logistics | 2020 |
| Minton Limited | Real estate | 2018 |
| Misty Willows Forest School CIC | Education | 2024 |
| MK7 Transport Ltd | Transport & logistics | 2016 |
| MLA Food Group Ltd | Manufacturing | 2024 |
| Modular Homes Limited | Construction | 2020 |
| Moniclean Ltd | Administrative & support | 2023 |
| Moomentum Limited | Arts & recreation | 2025 |
| Moose Group Holdings UK Ltd | Financial services | 2024 |
| Morgan Beach Bites Ltd | Hospitality | 2021 |
| Mostoghiu Ltd | Transport & logistics | 2020 |
| Motrade Limited | Wholesale & retail | 2024 |
| Moveunit Residents Management Limited | Households | 1987 |
| Mozwald Holdings Limited | Financial services | 2019 |
| MPW Trans Ltd | Transport & logistics | 2021 |
| MR Bees Brewery Ltd | Manufacturing | 2016 |
| MR Plant Geek Ltd | Wholesale & retail | 2021 |
| MR Tutor Ltd | Education | 2025 |
| MSM Event Staff Ltd | Administrative & support | 2020 |
| MTS (Holdings) Limited | Financial services | 1995 |
| Muhammad Shafiq Ltd | Wholesale & retail | 2025 |
| Multicats Limited | Transport & logistics | 2020 |
| Multimodal Logistics Limited | Transport & logistics | 2001 |
| Mumroom Ltd | Information & communication | 2020 |
| Munro Property Renovation Services Limited | Construction | 2009 |
| Music Counts Limited | Professional & scientific | 2019 |
| MVS BG Ltd | Transport & logistics | 2020 |
| MX Express Ltd | Transport & logistics | 2022 |
| My Festival CIC | Arts & recreation | 2017 |
| My Shop Ltd | Wholesale & retail | 2019 |
| Mybest Doner Ltd | Hospitality | 2023 |
| Myexec Ltd | Professional & scientific | 2024 |
| N F (Felixstowe) Ltd | Real estate | 2012 |
| Nara Projects Limited | Construction | 2014 |
| New Alliance Services Limited | Transport & logistics | 1981 |
| New P.T.S.Transport Ltd | Transport & logistics | 2025 |
| NG Rigging Limited | Construction | 2002 |
| Nice & Spice Felixstowe Ltd | Hospitality | 2019 |
| Nicholas Alexander Transport Ltd | Transport & logistics | 2018 |
| Nick Wright Services Limited | Administrative & support | 2012 |
| Nickvasil Haulage Ltd | Transport & logistics | 2022 |
| Nicu Andrei Ltd | Transport & logistics | 2026 |
| Nightingale Properties Trimley Limited | Households | 2018 |
| NIKI13 Ltd | Transport & logistics | 2021 |
| Niko-Bulpz Ltd | Transport & logistics | 2020 |
| Nimfas Transport Ltd | Transport & logistics | 2022 |
| Ninna Trans Limited | Transport & logistics | 2020 |
| Nithin Assets Ltd | Real estate | 2023 |
| Nithin Express Ltd | Wholesale & retail | 2022 |
| Nithin Ltd | Wholesale & retail | 2025 |
| Nithin Property Ltd | Real estate | 2026 |
| NKE Services Limited | Transport & logistics | 2018 |
| NKS Transport IMG Ltd | Transport & logistics | 2026 |
| NMC Global Logistics Limited | Transport & logistics | 2000 |
| NMS Builder Ltd | Construction | 2018 |
| NO. 6 Sea Road Ltd | Households | 2010 |
| Noctua AI Academy Ltd | Education | 2025 |
| Northcliffe Cybersecurity Research Ltd | Information & communication | 2019 |
| Northfleet Limited | Transport & logistics | 1983 |
| Nosydrecords Limited | Arts & recreation | 2017 |
| NOT Wasted Ltd | Wholesale & retail | 2025 |
| NRG Home Felixstowe Ltd | Real estate | 2024 |
| NRG Theatres Ltd | Professional & scientific | 2015 |
| NRK Services Ltd | Transport & logistics | 2025 |
| NSB Trans Ltd | Administrative & support | 2017 |
| NST Services UK Limited | Transport & logistics | 2017 |
| NTG Air & Ocean (UK) Ltd | Transport & logistics | 2002 |
| NTS Norbert Transport Service Ltd | Transport & logistics | 2017 |
| OAT Property Ltd | Real estate | 2020 |
| Occupied Software Limited | Information & communication | 2022 |
| Ocean Company Services Limited | Professional & scientific | 2001 |
| Oceanstar Logistics Limited | Transport & logistics | 2024 |
| Odinastrans Ltd | Transport & logistics | 2025 |
| ODY UK Forwarding and Trading Ltd | Wholesale & retail | 2017 |
| Ogi-Logistics Ltd | Transport & logistics | 2022 |
| OHRID4 Ltd | Transport & logistics | 2020 |
| Old Rectory (Felixstowe) Management Company Limited | Households | 2011 |
| Oliver's Inc Ltd. | Other services | 2010 |
| Olmar GB Ltd | Manufacturing | 2013 |
| Olsl Ltd | Administrative & support | 2015 |
| OMF East Ltd | Transport & logistics | 2018 |
| ON Your Sleeve Ltd | Wholesale & retail | 2024 |
| One Forex Ltd | Financial services | 2018 |
| One Piece Transports Ltd | Transport & logistics | 2019 |
| Open EHS Limited | Information & communication | 2013 |
| Operation Solutions Limited | Professional & scientific | 2013 |
| Optio Auctus Ltd | Administrative & support | 2026 |
| Orbital Transport Ltd | Transport & logistics | 2026 |
| Origin Global Logistics Limited | Transport & logistics | 2023 |
| Orobec Consulting Limited | Information & communication | 2015 |