| Mount Kellett Developments Ltd | Administrative & support | 2024 |
| Moveezo Limited | Transport & logistics | 2026 |
| Moveflex Ltd | Construction | 2018 |
| Mowat Court Management Limited | Households | 1987 |
| Mpcs Consulting Ltd | Information & communication | 2009 |
| MSA Property Holdings Ltd | Real estate | 2023 |
| Msmt Diagnostics & Maintenance Services Limited | Wholesale & retail | 2026 |
| MST Contracting Limited | Information & communication | 2021 |
| MSW Collectible UK Limited | Wholesale & retail | 2024 |
| Mtraining Solutions Limited | Education | 2012 |
| Municipal Clothing Ltd | Wholesale & retail | 2025 |
| Munim Ltd | Health & social care | 2016 |
| Mvth Ltd | Construction | 2024 |
| MW Motors International Ltd. | Manufacturing | 2015 |
| My Ikigai Sportswear Limited | Wholesale & retail | 2022 |
| My Key Ltd | Real estate | 2020 |
| MYA RK Salon Limited | Other services | 2024 |
| N B DRY Lining Limited | Construction | 2007 |
| Navemo Ltd | Information & communication | 2019 |
| Navraj Properties Ltd | Real estate | 2024 |
| NBY Advisory Ltd | Professional & scientific | 2026 |
| Network Cargo Limited | Transport & logistics | 2024 |
| Network Languages Limited | Administrative & support | 1996 |
| New Day Building Ltd | Construction | 2021 |
| New Imagination LAB Ltd | Professional & scientific | 2024 |
| New JOB Supermarket Limited | Administrative & support | 2012 |
| New Sunbury Limited | Hospitality | 2025 |
| Nice Food London Limited | Wholesale & retail | 2025 |
| Nicole & Naomi's Healthcare Ltd | Health & social care | 2014 |
| Nirmal and Sons Ltd | Hospitality | 2023 |
| NJL Comms Limited | Information & communication | 2022 |
| NJS Construction Services Limited | Administrative & support | 2022 |
| NM Portfolio Limited | Real estate | 2026 |
| Noctua Marketing Ltd | Professional & scientific | 2026 |
| Nomira Care Ltd | Health & social care | 2022 |
| Norman House Limited | Households | 2019 |
| Nova Aesthetics & Beauty Ltd | Other services | 2026 |
| Novaframe Aluminium Ltd | Construction | 2026 |
| Novello Products Limited | Wholesale & retail | 2017 |
| Novo Plumbing Ltd | Construction | 2024 |
| Nulife Advisors Ltd | Wholesale & retail | 2025 |
| NVJ Consulting Limited | Professional & scientific | 2017 |
| O W Productions Limited | Information & communication | 2019 |
| Oakdene Residents Association Limited | Households | 1968 |
| Obumu Limited | Transport & logistics | 2026 |
| Ocean Curry Ltd | Hospitality | 2020 |
| Ocean Protection and Restoration Consulting Ltd | Professional & scientific | 2025 |
| Ockham Group UK Ltd | Transport & logistics | 2021 |
| Odecam Limited | Administrative & support | 2018 |
| OFF the Top of My Head Limited | Professional & scientific | 2010 |
| Old Lodge Place (Twickenham) Management Limited | Households | 1988 |
| Oldfield Wines Ltd | Wholesale & retail | 2003 |
| OLY Drylining Ltd | Construction | 2019 |
| Onslow Residence RTM Company Limited | Households | 2011 |
| Onyx Electrical Installations Ltd | Construction | 2026 |
| Opal Water Limited | Water & waste | 2025 |
| Open Door Church Sunbury | Other services | 1999 |
| Open Heart Strategy Limited | Professional & scientific | 2023 |
| Operational Chef Consultant Limited | Hospitality | 2019 |
| Opportuna Consultancy Ltd | Information & communication | 2018 |
| Opportuna Investments Ltd | Real estate | 2023 |
| Optaria Ltd | Information & communication | 2015 |
| Opulence Events London Ltd. | Other services | 2017 |
| Orchard Lease and Finance Ltd | Professional & scientific | 2018 |
| Orston Limited | Professional & scientific | 2015 |
| Ottershaw Park Estate Company Limited | Households | 1981 |
| Ottershaw Park Woodland Limited | Households | 2007 |
| OUD Elements Ltd | Wholesale & retail | 2025 |
| OUR HR People (Sunbury) Limited | Professional & scientific | 2026 |
| Ouseley Lodge Management Company Limited | Households | 1974 |
| Outlaw Media Ltd | Information & communication | 2024 |
| Oxus Clinic Ltd | Health & social care | 2025 |
| P J Buck Cleaning Services Limited | Administrative & support | 2025 |
| P J Buck Garden and Exterior Services Limited | Administrative & support | 2017 |
| P&A Worldsprint Ltd | Transport & logistics | 2018 |
| P.C. Heasman & Co. Limited | Wholesale & retail | 1956 |
| PACUK12 Ltd | Wholesale & retail | 2019 |
| PAD Printer Limited | Manufacturing | 1995 |
| Paddock Gear & Engineering Limited | Manufacturing | 1999 |
| Paice Coachworks Limited | Wholesale & retail | 2026 |
| Paice MOT Limited | Wholesale & retail | 2025 |
| Paice Motors TW16 Limited | Wholesale & retail | 2025 |
| Panatec Limited | Information & communication | 2007 |
| Pankhania & Co Limited | Wholesale & retail | 2006 |
| Para Gold Services Limited | Administrative & support | 2019 |
| Paradise Flooring Ltd | Wholesale & retail | 2017 |
| Park House Management Solutions Limited | Households | 2016 |
| Park Road Studio Ltd | Arts & recreation | 2019 |
| Patriotic Dating Ltd | Administrative & support | 2026 |
| PC Cubed Ltd | Real estate | 2017 |
| PDF Real Estate Ltd | Real estate | 2026 |
| Pelican Sales and Marketing Ltd | Professional & scientific | 2009 |
| Pencil and Pixel Ltd | Professional & scientific | 2016 |
| Pepcon (UK) Limited | Construction | 1996 |
| Perennial Consulting Limited | Information & communication | 2014 |
| Perfectly Moved Limited | Transport & logistics | 2016 |
| Periodico Ltd | Wholesale & retail | 2021 |
| Pet Exports UK Limited | Transport & logistics | 2009 |
| Peter Crowther Associates Limited | Administrative & support | 2002 |
| Petram Limited | Financial services | 2025 |