| MSR Properties Ltd | Real estate | 2009 |
| MSR Telecoms House Ltd | Financial services | 2021 |
| Mtechtrade Ltd | Construction | 2024 |
| Munir Bro's 786 Ltd | Wholesale & retail | 2026 |
| Musgrave Holdings Limited | Professional & scientific | 2006 |
| Mustafa & Brothers Supermarket Ltd | Wholesale & retail | 2025 |
| MVM Global Ltd | Arts & recreation | 2022 |
| MXD Services Ltd | Information & communication | 2023 |
| Myskirtingboards Limited | Manufacturing | 2020 |
| Myup Limited | Professional & scientific | 2023 |
| N.C.S. Leisure Enterprises Limited | Arts & recreation | 2015 |
| Nagra Builders & Contractors Limited | Construction | 2007 |
| Naked Skin Aestheticsss Ltd | Other services | 2025 |
| Nalayntours Ltd | Administrative & support | 2026 |
| Natasha Shuard Management Ltd | Professional & scientific | 2019 |
| Nature's Best Services Ltd | Administrative & support | 2023 |
| Naunton Group Limited | Professional & scientific | 2023 |
| ND Support Services Limited | Professional & scientific | 2012 |
| Neal & Mcgrath Installations Limited | Construction | 2017 |
| Neal and Co Audit Services Limited | Professional & scientific | 2019 |
| Neal and Co Business Services Limited | Professional & scientific | 2004 |
| Neal and Co Financial Services Limited | Financial services | 2006 |
| Neal and Co Probate Services Limited | Professional & scientific | 2020 |
| Neal and Co Tax Services Limited | Professional & scientific | 2020 |
| Neil Johnson Building Services Limited | Construction | 2007 |
| Nela Trans Ltd | Transport & logistics | 2024 |
| Nell Gwynn Chelsea Accommodation Limited | Real estate | 2013 |
| Nell Gwynn House Freehold Limited | Households | 2007 |
| Nell Gwynn House Limited | Households | 2023 |
| Nerdata Solutions Ltd | Information & communication | 2022 |
| Nesvin Local Expess Ltd | Wholesale & retail | 2025 |
| Netherton Commercial MAC Ltd | Wholesale & retail | 2025 |
| Netherton Commercials Limited | Wholesale & retail | 1987 |
| Nets & Drapes Limited | Construction | 1991 |
| Network Cable & Pipe Supports Limited | Professional & scientific | 2003 |
| New Life Designs Ltd | Professional & scientific | 2024 |
| New Style Luxury Properties Ltd | Real estate | 2021 |
| Newey Construction Limited | Construction | 2005 |
| Newey Electrical Installations Limited | Construction | 1987 |
| Newey Electrical Supplies Limited | Wholesale & retail | 2024 |
| Newey Group Limited | Professional & scientific | 2009 |
| Newlands Catering (Midlands) Limited | Hospitality | 2024 |
| Newton Reed Limited | Transport & logistics | 2004 |
| NFS Dynamics Ltd | Wholesale & retail | 2013 |
| Nicholson Scapes Limited | Administrative & support | 2024 |
| Nick Stanford Limited | Professional & scientific | 2010 |
| Nil's 61. Ltd | Wholesale & retail | 2019 |
| Nilkpaul Limited | Administrative & support | 2025 |
| NJ Autos (Midlands) Limited | Wholesale & retail | 2025 |
| Nocte Limited | Health & social care | 2009 |
| NOR Vent Limited | Professional & scientific | 2000 |
| Norton Properties (Midlands) Limited | Real estate | 2024 |
| Norvent Group Ltd | Professional & scientific | 2014 |
| Norvent Pipework Limited | Construction | 2006 |
| Notifi Limited | Information & communication | 2003 |
| November 12 Productions Ltd | Information & communication | 2023 |
| NP Midlands Ltd | Hospitality | 2021 |
| NPS Design Engineering Limited | Professional & scientific | 2020 |
| NRG Heating & Plumbing Limited | Construction | 2023 |
| Nyle Corp Ltd | Wholesale & retail | 2022 |
| O P Fabrication Limited | Administrative & support | 2018 |
| Oak Engineering Company(Old Hill)Limited | Manufacturing | 1945 |
| Oakfield Trading Limited | Wholesale & retail | 2019 |
| Oakham Services Ltd | Professional & scientific | 2015 |
| Oaklea Steel Services Limited | Manufacturing | 2020 |
| OB Property Group Ltd | Real estate | 2025 |
| Ober Maintenance Ltd | Construction | 2026 |
| Oceanlight Limited | Wholesale & retail | 1990 |
| OH Baby Competitions Ltd | Wholesale & retail | 2025 |
| OH Baby Store Ltd | Wholesale & retail | 2025 |
| Oircle Ltd | Wholesale & retail | 2018 |
| Okaasan Properties Ltd | Real estate | 2023 |
| Old Hill Halal Meat Centre Ltd | Wholesale & retail | 2024 |
| Old Park Pro GAS Limited | Extraterritorial | 1999 |
| Old Rectory Tea Room Limited | Hospitality | 2024 |
| Oldbanque Property Holdings Limited | Professional & scientific | 2016 |
| Oldhill Retail Ltd | Wholesale & retail | 2022 |
| Olkay Corporation Limited | Financial services | 2006 |
| OMB Transport Ltd | Transport & logistics | 2019 |
| ON Prop Ltd | Real estate | 2025 |
| ON Route Trailer Care Ltd | Wholesale & retail | 2026 |
| ON Time Property Services Limited | Construction | 2024 |
| One Humanity Housing Ltd | Households | 2025 |
| One Stop Halesowen Road Ltd | Wholesale & retail | 2025 |
| One Team Construction Limited | Construction | 2022 |
| One to One Implant Training Ltd | Administrative & support | 2004 |
| Onley Garden Limited | Hospitality | 2021 |
| Opal Aura Limited | Manufacturing | 2013 |
| Optility Limited | Construction | 2022 |
| Orbit Bearings and Transmission Limited | Wholesale & retail | 1990 |
| Orbits IT Group EOT Limited | Professional & scientific | 2025 |
| Orbits IT Group Limited | Financial services | 2024 |
| Orchard Coaching and Consulting Ltd | Professional & scientific | 2020 |
| Organisational, Cleaning and Detailing Services Ltd | Administrative & support | 2020 |
| Ormerod Management Services Limited | Professional & scientific | 1998 |
| Orthotech (Orthodontic Appliances) Limited | Health & social care | 2002 |
| Oscars Doggy Stay N Play Ltd | Arts & recreation | 2021 |
| Over the Moon Couriers Ltd | Transport & logistics | 2024 |
| Owens Amusements Limited | Arts & recreation | 2025 |
| Oxford Safety Components Limited | Construction | 2000 |