| Mealing Taxis Limited | Administrative & support | 2002 |
| Medics With Hearts Ltd | Other services | 2010 |
| Mega Electric Holdings Limited | Information & communication | 2001 |
| Middlesex PG Limited | Administrative & support | 2011 |
| MIE Skincare Ltd | Wholesale & retail | 2022 |
| Migdal Emunah Ltd | Administrative & support | 2012 |
| Milford UK Properties Limited | Real estate | 2006 |
| Mill Reef Developments Limited | Construction | 1995 |
| Millennium II Limited | Arts & recreation | 2015 |
| Milsam Finance Limited | Financial services | 2023 |
| Mimma Viglezio Limited | Administrative & support | 2010 |
| Monèt Properties Ltd | Households | 2024 |
| Moorquest Limited | Financial services | 1973 |
| Morco Polo Empire Ltd | Wholesale & retail | 2021 |
| MRE Scooter Limited | Wholesale & retail | 2019 |
| Mrida Solutions Limited | Wholesale & retail | 2009 |
| MSU Estates Limited | Real estate | 2024 |
| MTM Bespoke Joinery Ltd | Construction | 2019 |
| MTR London Maintenance Ltd | Transport & logistics | 2013 |
| Mundus Properties Limited | Construction | 2004 |
| Muse Unique Ltd | Wholesale & retail | 2014 |
| My Trade Warriors Limited | Construction | 2019 |
| My Wings Ltd | Information & communication | 2022 |
| Myca LEE Limited | Administrative & support | 2009 |
| N-Vironment Limited | Real estate | 2001 |
| Nasm Ltd | Construction | 2017 |
| Natt Hotel Limited | Hospitality | 2014 |
| New Vintage Ltd | Wholesale & retail | 2013 |
| Newbury New Build Limited | Construction | 2014 |
| Newdrive Solutions Limited | Wholesale & retail | 1998 |
| Next Wave Hospitality Ltd | Professional & scientific | 2026 |
| Niallex Consulting Limited | Education | 2018 |
| Nicholas Templeman Ltd | Manufacturing | 2014 |
| Nilkanth Homes Ltd | Real estate | 2020 |
| Nldn Design Limited | Construction | 2024 |
| Norbury Holdings Limited | Construction | 1959 |
| Norfolk Boys Barber Shop Limited | Other services | 2018 |
| Nuts 4 Art Limited | Administrative & support | 2017 |
| O'Brien & Co Limited | Professional & scientific | 2010 |
| Oak Eden Limited | Real estate | 2025 |
| Oak Rugs Ltd | Wholesale & retail | 2023 |
| Obrela Holdco Limited | Financial services | 2016 |
| Obrela Limited | Information & communication | 2009 |
| Obrela Research and Development Limited | Professional & scientific | 2019 |
| Obrela Security Industries Limited | Professional & scientific | 2011 |
| Office Blind Systems Limited | Other services | 2004 |
| Official Watches Limited | Wholesale & retail | 2006 |
| Old Farmhouse Mews (Welham Green) Management Company Limited | Households | 2014 |
| Oldborough Ltd | Wholesale & retail | 1997 |
| Open Tree Investment Limited | Real estate | 2017 |
| Orient Translation Limited | Professional & scientific | 2003 |
| OTL Constantine Investments Limited | Financial services | 2023 |
| OTP Consultancy Ltd | Administrative & support | 2017 |
| Outdoor Solutions Consultancy Limited | Professional & scientific | 2010 |
| Outpost Limited | Wholesale & retail | 1987 |
| Oxford International Biomedical Centre Limited | Education | 1993 |
| Ozzi Trans Limited | Transport & logistics | 2019 |
| Papalino Limited | Hospitality | 2010 |
| Parade Developments Limited | Other services | 2017 |
| Paramount Services International (Liverpool) Limited | Real estate | 2018 |
| Paramount Services International Limited | Real estate | 2016 |
| Parkmore Property and Investment Co.Limited | Construction | 1963 |
| Pars Motors Finchley Limited | Wholesale & retail | 2024 |
| Patney Limited | Real estate | 1954 |
| Pawee Ltd | Hospitality | 2025 |
| PAZ Catering Limited | Hospitality | 2023 |
| Pedrian Limited | Financial services | 1978 |
| Peglington Productions Limited | Information & communication | 1984 |
| Perry Gardens Freehold Management Limited | Administrative & support | 2017 |
| Peter Fraenkel Ltd | Professional & scientific | 2011 |
| Pharma 777 Limited | Wholesale & retail | 2008 |
| Phoenix Capitol Holdings Ltd | Information & communication | 2022 |
| Pivot VR Limited | Administrative & support | 2015 |
| Plan Ahead Travel Limited | Transport & logistics | 2013 |
| Platinum Family Capital Limited | Other services | 2025 |
| Plumeblanche Limited | Professional & scientific | 2004 |
| Plus EX Ltd | Transport & logistics | 2023 |
| Polidor Group Holdings Limited | Construction | 2016 |
| Polidor TC Limited | Other services | 2014 |
| Polygon Consultancy Services Ltd | Administrative & support | 2017 |
| Portrait Software International Limited | Information & communication | 1986 |
| Practitioners Limited | Health & social care | 2006 |
| Pretty Ruff Limited | Professional & scientific | 2009 |
| Principex Limited | Wholesale & retail | 2000 |
| Priory Residents Association (Edgware) Limited | Households | 1986 |
| Private JET Charter Limited | Transport & logistics | 1995 |
| Private Label Dubai Limited | Wholesale & retail | 2020 |
| Property Risk Management Central Europe Ltd | Financial services | 2014 |
| Property Turkey for Sale.Com Limited | Real estate | 2007 |
| Property Turkey Limited | Extraterritorial | 2009 |
| PSC Global Ltd | Administrative & support | 2024 |
| Pugnax FX Capital Limited | Financial services | 2011 |
| Q M Solutions Limited | Administrative & support | 2008 |
| Qlvr Limited | Manufacturing | 2024 |
| Queenz Equestrian Limited | Education | 2018 |
| Queenz Team Limited | Arts & recreation | 2023 |
| Questus Solutions Ltd | Information & communication | 2012 |
| R. White Builders Limited | Construction | 2000 |
| Ramac Real Estate Ltd | Administrative & support | 2011 |
| Rapm Investments Limited | Construction | 2021 |