| Manufactured Romance | 1979 | — | — |
| Marconi Union | 2002 | — | — |
| Marillion | 1979 | — | British progressive rock band |
| Marine Girls | 1980 | 1983 | — |
| Marion | January 1993 | — | — |
| Mark–Almond | 1970 | — | — |
| Marmalade | 1966 | — | 60’s band |
| Marmozets | 1 June 2006 | — | — |
| Marseille | 1976 | 2019 | — |
| Marshall Law | 1987 | 2010 | — |
| Martin Stephenson and the Daintees | 1982 | — | — |
| Martin Turner’s Wishbone Ash | 2005 | 19 February 2014 | — |
| Maruja | 2014 | — | — |
| Marw | 2015 | — | — |
| Masiro | 2011 | — | — |
| Mass | 1980 | 1981 | — |
| Massive Attack | 1987 | — | — |
| Massive Violins | 2010 | — | — |
| Matchbox | 1971 | — | — |
| Matching Mole | October 1971 | September 1972 | — |
| Max Raptor | 2006 | — | — |
| Maxïmo Park | 2000 | — | English alternative rock band |
| May Blitz | 1969 | — | — |
| Maybeshewill | 2005 | — | — |
| Mayfield's Mule | 1968 | — | — |
| McAlmont & Butler | 1994 | 2006 | — |
| McCarthy | 1985 | 1990 | — |
| McFly | 2004 | — | English pop band |
| McGuinness Flint | 1970 | 1975 | — |
| Mclusky | 1996 | 7 January 2005 | — |
| Mediatrocity | 2008 | 2011 | — |
| Meet Me in St. Louis | 2005 | 2008 | — |
| Mega City Four | 1987 | April 1996 | — |
| Mega Emotion | 2013 | — | — |
| Mega Happy | 2017 | — | — |
| Mel & Kim | 1986 | 18 January 1990 | Appleby sisters |
| Memoriam | January 2016 | — | — |
| Menace | 1976 | — | — |
| Mesh | 1991 | — | — |
| Metabolist | 1977 | — | — |
| Metronomy | 1999 | — | — |
| Metropak | 1979 | 1980 | — |
| Michael Moorcock & the Deep Fix | 1975 | — | — |
| Microcosm | 1993 | — | — |
| Midas Fall | 2 August 2008 | — | — |
| Middle Finger Salute | 2005 | 2014 | — |
| Midnight Bonfires | 20 January 2011 | — | — |
| Midnight Configuration | 1993 | — | — |
| Midside | 1 April 2016 | — | — |
| Mighty Baby | 1969 | — | — |
| Mighty Mighty | 1983 | 1988 | — |
| Mike + the Mechanics | 1985 | — | — |
| Mike TV | 2008 | — | — |
| Milltown Brothers | 1989 | — | — |
| Mindfeed | 1996 | — | — |
| Ministers 4 Justice | 2010 | — | — |
| Minor Victories | 2015 | — | — |
| Minus the Intention | 23 September 2009 | — | — |
| Miranda Sex Garden | 1988 | — | — |
| Misanthropia | 2018 | — | — |
| Misery Addict | 6 October 2009 | — | — |
| MisophoniA | 2017 | — | — |
| Missarioty | 1 July 2011 | — | — |
| Misspent Youth | 1975 | — | — |
| Misty's Big Adventure | 1996 | — | — |
| Mithras | 1998 | — | — |
| Mo-Dettes | 1979 | 1982 | — |
| Models | 1977 | 1978 | — |
| Modern English | 1979 | — | — |
| Modestep | 2010 | — | — |
| Mogwai | 1995 | — | Scottish post‐rock band |
| Mojave 3 | 1994 | — | — |
| Moloch | 2007 | — | — |
| Monkey Swallows the Universe | January 2003 | 2008 | — |
| Monolith | 1991 | — | — |
| Monty Python | 1969 | July 2014 | British surreal comedy group |
| Monument | 1970 | — | — |
| Monument | 2011 | — | — |
| Monuments | 2007 | — | — |
| Moonari | 10 September 2013 | — | — |
| Moose | 1990 | 2000 | — |
| Moose Blood | August 2012 | 24 September 2018 | — |
| Morag Tong | 2014 | — | — |
| Morcheeba | 1995 | — | — |
| More | 1979 | 1983 | — |
| Morgue Orgy | 1 January 2008 | 2015 | — |
| Morning Myth | 1 February 2018 | — | — |
| Morning Runner | 2003 | 2007 | — |
| Morstice | 1992 | 1995 | — |
| Mortal Remains | 1989 | 1991 | — |
| Mortuary Spawn | 2020 | — | — |
| Moss | 2001 | — | — |
| Mostly Autumn | 1996 | — | — |
| Mother Earth | 1991 | — | — |
| Mott the Hoople | 1969 | 1974 | — |
| Motörhead | June 1975 | 28 December 2015 | — |
| Mount Fabric | 2007 | — | — |
| Mountain Caller | 2017 | — | — |
| Mouth | 2013 | — | — |
| Movietone | 1994 | — | — |