| M2 | Japan | August 8, 1991 | 15 | 4 |
| M2H | Netherlands | — | 3 | 3 |
| Machine Zone | United States | 2008 | 1 | 1 |
| Macmillan Inc. | United States | 1896 | — | 1 |
| Macmillan Publishers | United Kingdom | 1843 | — | 1 |
| MacPlay | United States | 1990 | — | 7 |
| Macromedia | United States | February 25, 1992 | — | — |
| MacSoft Games | United States | 1993 | 4 | 5 |
| Mad About Pandas | Germany | 2005 | 1 | — |
| Mad Catz | United States | 1989 | — | 1 |
| Mad Head Games | Serbia | — | 2 | 2 |
| Mad Monkey Studio | France | 2003 | 1 | 1 |
| Madfinger Games | Czech Republic | 2010 | 1 | — |
| MadMinute Games | — | 2001 | 1 | — |
| Madosoft | Japan | — | 1 | — |
| Magenta Factory | People's Republic of China | — | 3 | 2 |
| Magenta Software | United Kingdom | 1994 | 2 | — |
| Mages | Japan | July 7, 2006 | 12 | 11 |
| Magic Bytes | Germany | 1987 | — | 1 |
| Magic Cube | South Korea | — | 1 | 1 |
| Magic Design Studios | France | November 16, 2015 | 1 | — |
| Magic Pockets | France | 2000 | 10 | — |
| Magical Company | Japan | May 29, 1985 | 3 | 1 |
| Magmic Games | Canada | — | 1 | — |
| Magnussoft | Germany | 1984 | 25 | 25 |
| Majesco Entertainment | United States | 1986 | 1 | 28 |
| Major League Baseball Advanced Media | United States | June 2000 | — | 1 |
| Makura | Japan | 2005 | 2 | 1 |
| Malfador Machinations | United States | 1995 | 4 | 1 |
| Malibu Comics | United States | 1986 | 1 | — |
| Manaccom | Australia | 1986 | — | 1 |
| Manalith Studios | Brazil | 2018 | 1 | — |
| MangaGamer | Japan | 2008 | — | 39 |
| Mango Party | Taiwan | September 11, 2021 | — | 3 |
| Mango Protocol | Spain | 2013 | 1 | — |
| Maple Powered Games | Canada | — | 1 | — |
| Marmalade | Japan | — | 1 | 1 |
| Marmalade Game Studio | United Kingdom | 2016 | 4 | 4 |
| Marubeni | Japan | 1949 | — | 1 |
| Marvelous | Japan | 2003 | 17 | 37 |
| Marvelous Entertainment | Japan | June 25, 1997 | 12 | 26 |
| Masaya | Japan | 1985 | 4 | 8 |
| Masque Publishing | United States | — | — | 3 |
| Mass Media Inc. | United States | 1980 | 1 | — |
| MassHive Media | Indonesia | 2014 | 2 | 1 |
| Massive Development | Germany | October 1994 | 2 | — |
| Massive Miniteam | Germany | — | 1 | — |
| Massive Monster | Australia | — | 1 | — |
| Masterpiece | Japan | February 15, 1992 | 1 | — |
| Mastertronic | United Kingdom | 1983 | — | 6 |
| Mastertronic Group | United Kingdom | 2004 | — | 3 |
| Mastiff | United States | 2002 | — | 6 |
| Matrix Games | United Kingdom | 1999 | 1 | 14 |
| Matrix Interactive | People's Republic of China | — | — | 1 |
| Matrix Software | Japan | July 1994 | 12 | — |
| Matsushita Electric Industrial Co., Ltd. | Japan | 1935 | — | 1 |
| Mattel | United States | 1945 | 2 | 3 |
| Mattel163 | — | 2017 | 1 | — |
| Max Design | Austria | 1991 | 3 | 2 |
| Max Inferno | Canada | 2021 | 1 | — |
| Maximum Entertainment | Sweden | 2009 | — | 1 |
| Maximum Games | United States | 2009 | 1 | 4 |
| Maxis | United States | 1987 | 40 | 6 |
| Mayo Games | Russia | — | 1 | — |
| MC2 France | — | 2003 | — | 3 |
| MD Games | Poland | — | — | 2 |
| Mebius. | Japan | — | — | 1 |
| Medallion Games | United Kingdom | February 10, 2020 | 1 | — |
| Media Blasters | — | May 5, 1997 | — | 1 |
| Media Factory | Japan | December 1986 | 1 | 4 |
| Media Molecule | United Kingdom | January 4, 2006 | 3 | — |
| Media Rings | Japan | October 2, 1989 | 3 | 2 |
| Media Station | Japan | 1981 | 1 | — |
| Media.Vision | Japan | March 1993 | 11 | — |
| MediaKite | Japan | April 1991 | — | 1 |
| Mediamond | Finland | March 2000 | — | — |
| MediaQuest Holdings | Philippines | 1998 | — | 1 |
| Mediatonic | United Kingdom | September 15, 2005 | 3 | 1 |
| MediaWorks | Japan | 1992 | 1 | 2 |
| MediBang | Japan | January 27, 2014 | — | 1 |
| Medienhaus Oetinger | Germany | June 12, 1946 | — | 1 |
| Mediocre AB | Sweden | — | 1 | — |
| Mega Cat Studios | United States | 2015 | 8 | 1 |
| Mega Enterprise | Korea | 1998 | 1 | — |
| Mega9pixel | Russia | — | — | 1 |
| MegaHouse | Japan | March 2, 1962 | — | 1 |
| Melbot Studios | Spain | 2017 | 1 | — |
| Meldac | Japan | 1990 | — | 1 |
| Melonhead Games | Australia | 2017 | 1 | 1 |
| Melsoft Games | Belarus | 2008 | 3 | — |
| Memorable Games | Italy | 2013 | 1 | 2 |
| Mental Drink | New Zealand | — | 1 | 1 |
| Mentor InterActive (United States) | United States | — | — | 1 |
| Meridian’93 | Ukraine | 1993 | 1 | — |
| Meringue Interactive | United States | — | 1 | 1 |
| Merscom | — | 1993 | — | 1 |
| Messier Games | Brazil | — | 1 | — |
| Meta Platforms | United States | July 29, 2004 | 1 | 2 |
| Metacore Games | Finland | January 12, 2015 | 1 | 1 |
| Metia Interactive | New Zealand | 2003 | 1 | — |
| Metro Corporation | Japan | May 15, 1987 | 1 | 1 |
| Metro3D | United States | 1998 | — | 5 |
| Metropolis Software | Poland | 1992 | 3 | 1 |
| Mi'pu'mi Games | Austria | — | 3 | 2 |
| Micro Forté | — | 1985 | 2 | — |
| Micro Magic Inc. | United States | 1995 | 1 | — |
| Micro Power | United Kingdom | — | — | 1 |
| Microbird | Austria | 2020 | 1 | — |
| Microcabin | Japan | November 27, 1982 | 11 | 8 |
| Microdeal | United Kingdom | — | — | 3 |
| Microfolie's | France | 1992 | — | 1 |
| MicroGraphic Image | United States | 1983 | 1 | — |
| Microids Studio Lyon | France | July 20, 2021 | 1 | — |
| Microids Studio Paris | France | September 29, 2021 | 1 | — |
| Micronet | Japan | October 29, 1982 | — | 1 |
| MicroPlay Software | United States | August 1991 | — | 1 |
| MicroProse | United States | 1982 | 21 | 22 |
| Microsoft | United States | April 4, 1975 | 3 | 22 |
| Microsoft Casual Games | United States | — | 1 | — |
| Microsoft Japan | Japan | 1986 | — | 1 |
| MiCROViSion Inc. | Japan | December 1986 | 1 | — |
| Midas Interactive Entertainment | United Kingdom | 1998 | — | 3 |
| Midoki | United Kingdom | December 14, 2011 | 1 | — |
| Midway Austin | United States | March 23, 2000 | 3 | — |
| Midway Games | United States | 1988 | 28 | 68 |
| Midway Home Entertainment | United States | 1994 | — | 1 |
| Midway Studios San Diego | United States | 2009 | — | — |
| Midway Studios – Los Angeles | United States | 1994 | 4 | — |
| Midway Studios – Newcastle | United Kingdom | 1996 | 5 | — |
| Might and Delight | Sweden | 2010 | 4 | 4 |
| Mighty Bear Games | Singapore | 2016 | 2 | 1 |
| Mighty Kingdom | Australia | 2010 | 1 | — |
| Mighty Polygon | Spain | — | 1 | — |
| Mighty Rocket Studio | — | 1999 | 2 | — |
| Mighty Yell | Canada | — | 1 | — |
| Mikro-Gen | United Kingdom | 1981 | 3 | 5 |
| Milestone | Japan | 2003 | 5 | 4 |
| Milestone S.r.l. | Italy | 1994 | 39 | 30 |
| Military Simulations | United States | 1994 | 1 | 1 |
| Milkstone Studios | Spain | — | 5 | 5 |
| Millennium Kitchen | Japan | December 1997 | 6 | — |
| Minato Soft | Japan | 2006 | 2 | — |
| Mindscape | United States | 1983 | 5 | 33 |
| Mindware Studios | Czech Republic | 2001 | 1 | — |
| Miniboss | Canada | — | 1 | — |
| Minicactus Games | Brazil | 2021 | 10 | 10 |
| Miniclip | Switzerland | 2001 | — | 3 |
| Minnesota Educational Computing Consortium | United States | 1973 | 6 | 3 |
| Minor Key Games | United States | July 15, 2013 | 3 | 3 |
| Minori | Japan | April 2007 | 6 | 3 |
| Mintrocket | South Korea | — | 1 | — |
| Mirage Media S.C. | Poland | — | 2 | — |
| Mirrorsoft | United Kingdom | 1982 | — | 6 |
| Mischief | United States | — | 1 | 1 |
| Mistic Software | Canada | — | 2 | — |
| Mistwalker | United States | 2004 | 1 | 1 |
| Mitchell Beazley International | United Kingdom | July 1969 | — | 1 |
| Mitchell Corporation | Japan | February 1960 | 3 | — |
| Mobile21 | Japan | 1999 | 2 | — |
| Mobirix | South Korea | March 2004 | — | 3 |
| Mode 7 | United Kingdom | 2005 | 2 | 3 |
| Modus Games | United States | — | — | 18 |
| Moe App | Japan | 2011 | — | 7 |
| Moe Fantasy | People's Republic of China | — | — | 1 |
| Mojang Studios | Sweden | 2009 | 8 | 3 |
| Mojiken Studio | Indonesia | 2013 | 3 | — |
| Molleindustria | Italy | December 2003 | 1 | 1 |
| Mommy's Best Games | United States | 2007 | 6 | 5 |
| Momo-pi | Switzerland | February 5, 2018 | 2 | 1 |
| Monkey Bar Games | United States | 2005 | 2 | — |
| Monkey Craft | Japan | — | 6 | — |
| Monochrom | Austria | 1993 | 1 | — |
| Monochrome Paris | France | — | 1 | — |
| Monochrome, Inc | United States | — | 3 | 3 |
| Monokel | Germany | — | 1 | — |
| Monolith Productions | United States | October 25, 1994 | 11 | 3 |
| Monolith Soft Inc. | Japan | October 1999 | 18 | — |
| Monomi Park | United States | 2014 | 2 | 2 |
| Monsta Studios | Malaysia | September 15, 2009 | — | 1 |
| Monstars | Japan | October 20, 2011 | 2 | — |
| Monster Games | United States | 1996 | 7 | — |
| Monsterland | Sweden | September 1999 | 3 | — |
| Monte Cristo | France | May 24, 1995 | 8 | 4 |
| Moon Studios | Austria | 2010 | 2 | — |
| Moonbyte Games | Germany | — | 1 | — |
| Mooneye Studios | Germany | — | — | 1 |
| Moonfrog | India | November 22, 2013 | 1 | — |
| Moonshot Games | United States | 2020 | 1 | — |
| Moonstone | Japan | 2003 | 6 | 4 |
| Morningstar Game Studio | United States | — | 2 | 1 |
| Morphcat Games | Germany | — | 1 | — |
| Morteshka | Russia | May 2015 | 1 | — |
| MOSS | Japan | 1993 | 8 | 3 |
| Mother Gaia | Brazil | 2008 | 4 | — |
| Motion Twin | France | August 6, 2001 | 4 | 3 |
| Motive Studio | Canada | July 13, 2015 | 2 | — |
| Motivetime Ltd. | United Kingdom | — | 1 | — |
| Motorsport Games | United States | — | 3 | 3 |
| MoveGames | South Korea | May 2002 | 2 | 1 |
| Movic | Japan | 1983 | — | 1 |
| Movie Games | Poland | — | — | 1 |
| Moving Pieces Interactive | United States | — | 2 | 2 |
| Mr Chip Software | United Kingdom | 1982 | 1 | — |
| MR-Software GbR | Germany | — | 1 | — |
| Mr. Nutz Studio | France | — | 2 | — |
| MTO | Japan | May 28, 1996 | 5 | 1 |
| MTV | United States | August 1981 | — | 4 |
| MTV Games | United States | 2005 | — | 6 |
| MuchDifferent | — | 2008 | 1 | — |
| Mucky Foot Productions | United Kingdom | 1997 | 1 | — |
| MumboJumbo | United States | 2001 | 29 | 16 |
| Muse Software | United States | 1978 | 2 | 2 |
| Muzzy Lane | United States | — | 2 | 2 |
| My.com | Netherlands | 2012 | — | 1 |
| My.Games | — | 2006 | 1 | 4 |
| MyDearest | Japan | April 2016 | 1 | 1 |
| Mynet | Japan | June 14, 2006 | 1 | 1 |
| Myroid-Type Comics | United States | — | 2 | 2 |
| Mystery Studio | — | 2002 | 1 | — |
| Mythic Entertainment | United States | 1995 | 2 | — |
| Mythos Games | United Kingdom | 1988 | — | — |
| Mytona | — | 2012 | — | 1 |