| Moallemi Holdings Ltd | Real estate | 2019 |
| Molinari Academy of Osteopathic Medicine Ltd | Health & social care | 2012 |
| Molton Toffee Operations Ltd | Manufacturing | 2014 |
| Montesano Care Ltd | Administrative & support | 2017 |
| Moore Horses Ltd | Arts & recreation | 2024 |
| Moore Investment Opportunities Ltd | Real estate | 1999 |
| More Stories Ltd | Professional & scientific | 2024 |
| More Wine Ltd | Wholesale & retail | 2018 |
| Mortazavi Enterprises Ltd | Real estate | 2024 |
| Mortgage & Lending Solutions Ltd | Financial services | 2003 |
| Mostamand Ltd | Transport & logistics | 2017 |
| Motor RGS Limited | Wholesale & retail | 2020 |
| Mousavi Holdings Ltd | Real estate | 2016 |
| Moving Home Surveys Ltd | Other services | 2023 |
| MSI Commercials Ltd | Transport & logistics | 2018 |
| Mtrh Developments Ltd | Real estate | 2013 |
| Muhadri Properties Ltd | Real estate | 2023 |
| Mukun Properties Ltd | Real estate | 2024 |
| Mulberry Eco Build Ltd | Construction | 2025 |
| Mulberry Holdings (Sussex) Limited | Financial services | 2018 |
| Mulberry Lane Ditchling Limited | Professional & scientific | 1989 |
| Mulberry Wines Ltd | Wholesale & retail | 2012 |
| Murelly Ltd | Other services | 2017 |
| Muscle Distributing Limited | Other services | 2015 |
| Musicademy Records Limited | Information & communication | 2005 |
| Muzza Group Ltd | Construction | 2024 |
| MW Paraplanning Limited | Administrative & support | 2026 |
| MWM Capital Limited | Real estate | 2019 |
| Mxch Ltd | Arts & recreation | 2021 |
| Mxmrv Ltd. | Professional & scientific | 2020 |
| My Little Farm Limited | Agriculture & fishing | 2020 |
| My Wonder Limited | Manufacturing | 2007 |
| N Harris Ltd | Construction | 2012 |
| Nail Garden and Spa Ltd | Other services | 2016 |
| Nail IT Newlyn Limited | Other services | 2010 |
| NAM Hove Limited | Hospitality | 2018 |
| Nanz Life Science Ltd | Wholesale & retail | 2020 |
| Natural Fit Gym Limited | Real estate | 2017 |
| Navaz Investments Ltd | Real estate | 2023 |
| Nayna Head Spa Ltd | Other services | 2025 |
| Neekadri Oral Care Ltd | Health & social care | 2013 |
| Nekoei Locum Services Limited | Health & social care | 2003 |
| Nellies Swim Limited | Wholesale & retail | 2026 |
| Nelson Property Investments Limited | Real estate | 1998 |
| Nest Home Renovation Limited | Construction | 2025 |
| NET Focus Limited | Information & communication | 1998 |
| Netweb Limited | Extraterritorial | 1997 |
| Neurodevelopmental Services Limited | Health & social care | 2019 |
| New Inn Events Limited | Hospitality | 2013 |
| New Street Ventures Limited | Real estate | 2025 |
| Newtimber Estate Limited | Agriculture & fishing | 2010 |
| Next Trails Ltd | Administrative & support | 2026 |
| Nicola Optics Ltd | Wholesale & retail | 2019 |
| Night Ground Ltd | Other services | 2010 |
| NIO Comm Ltd | Construction | 2008 |
| NIO Energy Holdings Ltd | Financial services | 2024 |
| NIO Energy Solutions Ltd | Construction | 2024 |
| NIO Evolution Limited | Construction | 2022 |
| NIO Group Ltd | Professional & scientific | 2008 |
| NIO Holdings Limited | Financial services | 2025 |
| NIO NET Ltd | Administrative & support | 2019 |
| NIO Revolution Limited | Construction | 2022 |
| NIO Self Hire Tools Ltd | Administrative & support | 2008 |
| NIO Services Ltd | Administrative & support | 2020 |
| NIO Shared Services Ltd | Administrative & support | 2024 |
| NIO Training Ltd | Education | 2024 |
| NMI Group Ltd | Construction | 2023 |
| NO Ordinary Ventures Ltd | Hospitality | 2025 |
| Noah's Angels Limited | Other services | 2026 |
| Noco Health Ltd | Health & social care | 2022 |
| North Park Farm Limited | Agriculture & fishing | 1977 |
| North Star Sussex Limited | Wholesale & retail | 1996 |
| Noted Ventures Ltd | Information & communication | 2025 |
| Nova Haus Ltd | Construction | 2025 |
| Novus Property Management Limited | Real estate | 2001 |
| Nrgroupltd Ltd | Construction | 2024 |
| NTB Enterprise Ltd | Wholesale & retail | 2019 |
| Nyes Hill Properties Ltd | Real estate | 2015 |
| Oakland Site Investigation Limited | Construction | 2012 |
| Oakwell Residents Company Limited | Households | 2014 |
| Obay Homes Limited | Construction | 2021 |
| OC Services (UK) Limited | Administrative & support | 2007 |
| OCD Auto Spa Limited | Wholesale & retail | 2017 |
| ODD Spider Ltd | Information & communication | 2025 |
| ODE & Ettle Ltd | Professional & scientific | 2025 |
| OEH Associates Limited | Real estate | 2018 |
| OEH Consulting Limited | Professional & scientific | 2020 |
| OH My Dog 247 Limited | Other services | 2023 |
| Oh-So Edtech Ltd | Information & communication | 2025 |
| Ondemand CFO Limited | Professional & scientific | 2017 |
| One Eleven Holdings Limited | Real estate | 2020 |
| Open Water Publishing Ltd | Information & communication | 2024 |
| Openstake Property Management Limited | Households | 1988 |
| Oradian Limited | Professional & scientific | 2014 |
| Orange Vehicle Rental Limited | Administrative & support | 2018 |
| Organic Corner Shop Ltd | Wholesale & retail | 2019 |
| Original Department Ltd | Administrative & support | 2025 |
| Oswald Property Investments Limited | Real estate | 2019 |
| OTC Direct (Structured Products) Limited | Professional & scientific | 2024 |
| OUR Little Thing Limited | Health & social care | 2016 |