| Majo Properties Ltd | Real estate | 2026 |
| Males' Mutts Ltd | Other services | 2023 |
| Manukamad Ltd | Information & communication | 2022 |
| Mark Scruton Design Ltd | Information & communication | 2025 |
| Martin Finance Limited | Financial services | 2024 |
| Matt Simmo Ltd | Information & communication | 2024 |
| Mattjamesboyle Ltd | Information & communication | 2022 |
| Maven Strategic Advice & Funding Solutions Limited | Financial services | 2016 |
| Medical GAS Testing Services Limited | Professional & scientific | 2003 |
| MEL Talks Ltd | Professional & scientific | 2021 |
| Meristem Developments Ltd | Construction | 2026 |
| Merlin Films Ltd | Information & communication | 2022 |
| MF London Limited | Professional & scientific | 2025 |
| MG Smart Ltd | Wholesale & retail | 2019 |
| MGA Carpentry Ltd | Information & communication | 2022 |
| MHE SET Rigging Ltd | Information & communication | 2011 |
| Microcosm Research Limited | Information & communication | 1981 |
| Midori BIO Ltd | Professional & scientific | 2024 |
| Mildot Ltd | Information & communication | 2024 |
| Milleeney Building Services Ltd | Construction | 2016 |
| Missi London Ltd | Wholesale & retail | 2013 |
| Mitro Consultancy Ltd | Administrative & support | 2012 |
| MJM Development Holdings Limited | Real estate | 2024 |
| MLB60 Draughting Ltd. | Professional & scientific | 2017 |
| Monarc Cottages Ltd | Real estate | 2022 |
| Montague Court (South Woodford) Management Co Limited | Households | 1995 |
| Moscenic Limited | Information & communication | 2015 |
| Moulton Holdings Limited | Real estate | 2019 |
| MSP Plastering Limited | Construction | 2012 |
| Murray Grant Limited | Information & communication | 2014 |
| Must Wine Hampstead Ltd | Hospitality | 2021 |
| Must Wine Islington Ltd | Hospitality | 2023 |
| Must Wine Wanstead Limited | Hospitality | 2021 |
| My Friday Story Ltd | Wholesale & retail | 2025 |
| Mylo Energy Ltd | Construction | 2023 |
| MYR Property Services Ltd | Real estate | 2022 |
| N & T Group Limited(The) | | 1956 |
| N M Umbrella Ltd | Administrative & support | 2017 |
| N&A Property Development Limited | Extraterritorial | 2020 |
| Nares International Limited | Transport & logistics | 1993 |
| NCW Consultants Ltd | Professional & scientific | 2025 |
| Neil Rodgie Plumbing & Heating Ltd | Construction | 2025 |
| Nick's Restaurant (Hampshire) Limited | Hospitality | 2011 |
| Ningenius Ltd | Professional & scientific | 2009 |
| NJB Scenery Ltd | Information & communication | 2024 |
| Nord Grips Ltd | Information & communication | 2023 |
| Nordic Locums Ltd | Professional & scientific | 2020 |
| Notchcentral Property Management Limited | Households | 2000 |
| Nous Metis Ltd | Professional & scientific | 2023 |
| Nsac Ltd | Construction | 2025 |
| O Master Ltd | Wholesale & retail | 2021 |
| Ollymarjstag Ltd | Information & communication | 2024 |
| ON SET Stagging Ltd | Information & communication | 2012 |
| One to Wine Ltd. | Hospitality | 2015 |
| Oparoa Ltd | Real estate | 2022 |
| Optical-Disc Supplies Limited | Manufacturing | 2012 |
| Optimal Nexus Ltd | Information & communication | 2024 |
| Oredein Solutions Limited | Information & communication | 2024 |
| Ortho Authority Ltd | Information & communication | 2025 |
| OS International Limited | Wholesale & retail | 2025 |
| Otterburn Management Company Limited | Households | 2006 |
| Overload Industry Ltd | Manufacturing | 2024 |
| Oxygen Capital Investment Ltd | Real estate | 2022 |
| P J Sets Ltd | Information & communication | 2016 |
| P&R Roofing Contractors Ltd | Real estate | 2017 |
| Painting With Light Limited | Other services | 2010 |
| Palm Graphics Limited | Arts & recreation | 2001 |
| Paul Tingley Carpentry Ltd | Information & communication | 2022 |
| PCJ Rigging Services Limited | Information & communication | 2016 |
| PDM Studio Limited | Administrative & support | 2018 |
| Peak Life Ltd | Hospitality | 2024 |
| Pear Orchard Property Ltd | Real estate | 2022 |
| Penne Close Management Limited | Households | 1993 |
| Pentomino Ltd | Information & communication | 2018 |
| Percy and Zuko Property Solutions Ltd | Real estate | 2024 |
| Personality Investigations Publications &Services Limited | Other services | 1972 |
| Petarmax Verification Ltd | Professional & scientific | 2022 |
| Peterside Group Holding Ltd | Real estate | 2016 |
| Peterside Haven Ltd | Hospitality | 2025 |
| Peterside Trading Co. Ltd | Construction | 2024 |
| Petraco Ltd | Construction | 2025 |
| Phoenix Hydro Ltd | Energy | 2023 |
| Phwh Properties Ltd | Real estate | 2023 |
| Pick My Property Ltd | Real estate | 2023 |
| Pine Film Services Limited | Information & communication | 2014 |
| Pitlane Limited | Wholesale & retail | 1997 |
| Portland Place Investments Ltd | Real estate | 2026 |
| Powerworks UK Electrical Services Limited | Energy | 2012 |
| Practical Spark Ltd | Construction | 2024 |
| Primo Production Ltd | Information & communication | 2024 |
| Probus Aviation Limited | Administrative & support | 2013 |
| Professional Services and Solutions Ltd | Information & communication | 2013 |
| Prox Ltd | Construction | 2024 |
| Quadrant Estates and Car Parking Ltd | Transport & logistics | 2026 |
| Qvevri Limited | Hospitality | 2017 |
| R & D TV and Film Ltd | Information & communication | 2021 |
| R & L Service & Repair Ltd | Wholesale & retail | 2010 |
| R E H Construction Ltd | Construction | 2010 |
| R-Is Consulting Services Ltd | Professional & scientific | 2024 |
| R. Stuckey Carpentry Services Ltd | Information & communication | 2023 |