| 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 |
| N-Fusion Interactive | United States | 1998 | 3 | — |
| N-Space | United States | 1994 | 15 | — |
| N3TWORK | United States | 2013 | 1 | 1 |
| N3V Games | Australia | 1995 | 3 | 1 |
| Nacon | France | February 5, 1981 | — | 38 |
| Nacon | France | July 12, 2019 | — | 18 |
| Nadeo | France | November 27, 2000 | 15 | — |
| Namco | Japan | June 1955 | 127 | 166 |
| Namco Bandai Games America Inc. | United States | — | — | 2 |