| Me Group International PLCEpsom, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1962 |
| Meadow Foods LtdChester, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1992 |
| Mechanised Project ManagementLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1946 |
| Mecm, LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1996 |
| Medagio LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2016 |
| Metmix LimitedUnited Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1990 |
| Mi Doudou LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2019 |
| Microsoft LimitedReading, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1982 |
| Mid Atlantic Productions LtdPyrford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1987 |
| Milestone LtdUnited Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2003 |
| Millbank Financial Services LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1986 |
| Mills & Reeve LLPLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2007 |
| Mindshare Media UK LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1997 |
| Mission Bay LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2011 |
| Mitchell Potatoes LtdRugby, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1980 |
| Model Farm Shop Ltd.Bradford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2012 |
| Modern Contradiction LimitedShrewsbury, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2017 |
| Moke Fine Wines LtdCirencester, United Kingdom · UKmokefinewines.co.uk · checked 28 Oct 2026 | UK | 1 | – | – | – | – | 2010 |
| Moncharm LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2007 |
| Mondrian LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1998 |
| Monex Europe LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2006 |
| Montealegre Company LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2015 |
| Montesion LimitedRadstock, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2024 |
| Monument Group Europe LLPLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2012 |
| Moonpig.com LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1999 |
| Mossman Family Import Company LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2014 |
| Mother London LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2003 |
| Mr Lawrence Wine Merchants LtdBishop's Stortford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2002 |
| Multimarvel UK LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2024 |
| Musicmann LtdWalsall, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2006 |
| Mutley Leisure LimitedChesterfield, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2021 |
| Mw Love Trading LtdHitchin, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2025 |
| Mxn Wines LtdFraserburgh, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2025 |
| My Dewine LtdAmersham, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2021 |
| N10 Bourbons LtdIlford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2018 |
| National Tube Stockholders LimitedNr Thirsk, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1985 |
| Navium Marine LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2021 |
| Nectar Imports LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1990 |
| Net Gain LtdBurnley, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1994 |
| Netflix Services UK LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2014 |
| Newrest-All LtdSlough, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2010 |
| Nigel Burgess LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1975 |
| Nike Mercurial I LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1924 |
| Nisbets LimitedBristol, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1983 |
| Nli Operator LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2008 |
| Nobilia Gb LimitedRochdale, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1999 |
| Norden Communication UK LtdClacton on Sea, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2006 |
| Norsk European Wholesale LimitedSlough, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1993 |
| Northend Solutions LtdBarnet, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2023 |
| Northumberland Events LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2009 |