| Monaco Engineering Solutions Limited | Mining & quarrying | 2006 |
| Monika Selecka Limited | Professional & scientific | 2018 |
| Monroe Global Trading Limited | Financial services | 2024 |
| Mooi Limited | Professional & scientific | 2019 |
| Moondance Advisors Ltd | Professional & scientific | 2022 |
| Moore Bookkeeping Limited | Professional & scientific | 2016 |
| Moorland Court Residents Association Limited | Households | 1985 |
| MOR Trim Ltd | Wholesale & retail | 2021 |
| Mother Earth Music Group Limited | Information & communication | 2025 |
| Motion Sports & Entertainment Limited | Professional & scientific | 2009 |
| Moto Technics Ltd | Wholesale & retail | 2019 |
| Motormaster Limited | Transport & logistics | 2003 |
| Mova Logistics Ltd | Transport & logistics | 2025 |
| Move Nourish Change Limited | Other services | 2013 |
| Move With LBP Ltd. | Education | 2018 |
| Movetouk Ltd | Information & communication | 2020 |
| Movie Logistics Ltd | Administrative & support | 2025 |
| Movie Movers Logistics Ltd | Administrative & support | 2024 |
| Mowtivated Application Limited | Information & communication | 2025 |
| Mowtivated Limited | Administrative & support | 2014 |
| MPA Contractors Ltd | Construction | 2023 |
| Mped Bethel Ltd | Health & social care | 2013 |
| MPI Properties Limited | Real estate | 2021 |
| MRS Hyde Ltd | Wholesale & retail | 2018 |
| MSC Audio Visual Ltd | Construction | 2026 |
| MSG Promotions Limited | Wholesale & retail | 2025 |
| Msks Technologies Limited | Information & communication | 2026 |
| Mtsheleli Investments Limited | Real estate | 2023 |
| Mulberry Court (Ashtead) Residents Association Limited | Households | 1973 |
| Multibot Ltd | Information & communication | 2024 |
| Multizone Limited | Information & communication | 1998 |
| Museum Mounts Ltd | Arts & recreation | 2020 |
| Music Lessons Limited | Education | 2025 |
| MXM Consulting Ltd | Professional & scientific | 2022 |
| My Clinic Supply Limited | Wholesale & retail | 2018 |
| My Pharma Medic Ltd | Professional & scientific | 2024 |
| Mydas PEN Entertainment Ltd | Information & communication | 2020 |
| Mykindacrowd Limited | Information & communication | 2010 |
| Mykindafuture Limited | Education | 2015 |
| Mysmart Investments Limited | Real estate | 2005 |
| Myti Ltd | Wholesale & retail | 2018 |
| N J Waple Associates Ltd | Professional & scientific | 2015 |
| N4NOVA Limited | Wholesale & retail | 2026 |
| Naan Dukaan Ltd | Hospitality | 2025 |
| Nadairx Ltd | Health & social care | 2026 |
| Nancy's Doggy Daycare Ltd | Other services | 2020 |
| NARR8 AI Ltd | Information & communication | 2026 |
| Nasa Data Systems Limited | Wholesale & retail | 2001 |
| Nasa International Limited | Wholesale & retail | 1989 |
| Nascorp Ltd | Other services | 2013 |
| Nash Abraham Legal Ltd | Professional & scientific | 2023 |
| Natura Homes Ltd | Real estate | 2019 |
| Naturalkey Property Management Limited | Households | 1986 |
| Naturally Amazing Ltd | Transport & logistics | 2015 |
| Navigate Marketing Ltd | Professional & scientific | 2023 |
| Navigilant Ltd | Other services | 2018 |
| Navigilant Technology Ltd | Information & communication | 2023 |
| Navirra Crew Limited | Administrative & support | 2026 |
| Neat Finish Limited | Construction | 2021 |
| NEC Telecom Modus, Ltd. | Information & communication | 1998 |
| Needspace? Limited | Real estate | 2005 |
| NEG Advisory Ltd | Professional & scientific | 2026 |
| Neighbourhood Barbers Ltd | Other services | 2026 |
| Neil Wilson Enterprises Limited | Information & communication | 1982 |
| Neolinea Limited | Wholesale & retail | 2024 |
| Nephrostomy UK Ltd | Wholesale & retail | 2019 |
| Neroli Limited | Wholesale & retail | 2013 |
| Nestara Ltd | Real estate | 2025 |
| Netzero Collective Limited | Construction | 2000 |
| Netzero Protocol Ltd | Information & communication | 2015 |
| Neuroconomy Limited | Other services | 2016 |
| New Leaf for Gardens Limited | Administrative & support | 2009 |
| New Partnerships Ltd | Health & social care | 2007 |
| Newcastle Consortium Supporters Ltd | Administrative & support | 2020 |
| Newlands Construction Group EOT Limited | Administrative & support | 2023 |
| Newlands Construction Group Limited | Construction | 2023 |
| Nextstepuk Ltd | Administrative & support | 2025 |
| Nexus Consultancy Services Limited | Professional & scientific | 2024 |
| Nexus First Limited | Professional & scientific | 2020 |
| Nexuscove Limited | Information & communication | 2023 |
| Nfma Limited | Information & communication | 2013 |
| NIA Success Ltd | Real estate | 2019 |
| Niakra Properties Ltd | Real estate | 2020 |
| Nicholls Marine Ltd | Manufacturing | 2024 |
| Nightingale Carpentry and Joinery Limited | Construction | 2011 |
| Nine Berrymead Gardens Residential Management Company Limited | Households | 2018 |
| Nine Owls Limited | Financial services | 2021 |
| Nine Seven Five Ltd | Information & communication | 2016 |
| Nirae Ltd | Other services | 2025 |
| Nirvana Veedub Camper Hire Ltd | Administrative & support | 2022 |
| Nizam & Team Limited | Other services | 2014 |
| NJB Renovations Ltd | Construction | 2013 |
| NMA Retail Ltd | Wholesale & retail | 2023 |
| Nmopq Limited | Professional & scientific | 2025 |
| Noamoa Limited | Arts & recreation | 2011 |
| Noisy OWL Limited | Construction | 2018 |
| Nomad Players Limited | Arts & recreation | 1974 |
| Noodle HR Ltd | Professional & scientific | 2019 |
| Norfolk Mansions (Wandsworth) RTM Company Limited | Households | 2013 |
| Norly Foods Ltd | Manufacturing | 2022 |