| M2 | Chiba | August 8, 1991 | video game industry |
| Machine Studios | — | 2014 | — |
| Machine Zone | Palo Alto | 2008 | — |
| Macmillan Inc. | New York City | 1896 | — |
| Macromedia | San Francisco | February 25, 1992 | software industry |
| Macsen Software | — | 1983 | — |
| Mad About Pandas | Berlin | 2005 | video game industry |
| Mad Fellows | Leamington Spa | 2013 | — |
| Mad Head Games | Novi Sad | — | video game industry |
| MadMinute Games | United States | 2001 | — |
| Madosoft | — | — | video game industry |
| Magenta Factory | — | — | — |
| Magic Cube | Busan | — | video game industry |
| Magic Pockets | Paris | 2000 | video game industry |
| Magical Company | Kobe, Chūō-ku | May 29, 1985 | video game industry |
| Magmic Games | — | — | — |
| Magnetic Fields | Chester | 1982 | — |
| Magnussoft | Kesselsdorf | 1984 | video game industry |
| Majestic Studios | — | — | — |
| Major Developments | — | — | — |
| Major League Baseball Advanced Media | New York City | June 2000 | mass media |
| Makura | — | 2005 | video game industry |
| Manaccom | Queensland | 1986 | software industry |
| Manalith Studios | Curitiba | 2018 | video game industry |
| Maple Powered Games | — | — | — |
| Marmalade | — | — | video game industry |
| Marmalade Game Studio | London | 2016 | — |
| Martech Games | Pevensey | 1982 | — |
| Marubeni | Tokyo | 1949 | sōgō shōsha |
| MassHive Media | Bandung | 2014 | video game industry |
| Massive Development | Mannheim | October 1994 | video game industry |
| Massive Miniteam | Pulheim | — | video game industry |
| Massive Monster | — | — | video game industry |
| Masterpiece | Tokyo | February 15, 1992 | — |
| Mastertronic Group | Huntingdon | 2004 | video game industry |
| Mastiff | Tokyo | 2002 | video game industry |
| Matrix Software | Shinjuku | July 1994 | video game industry |
| Mattel163 | El Segundo | 2017 | — |
| Maximum Games | Walnut Creek | 2009 | video game industry |
| Maxis | Emeryville | 1987 | video game industry |
| MD Games | Warsaw | — | video game industry |
| MDickie Limited | — | — | — |
| Media Blasters | New York City | May 5, 1997 | horror film |
| Media Factory | Shibuya | December 1986 | video game industry |
| Media Molecule | Guildford | January 4, 2006 | — |
| Media Station | Tokyo | 1981 | pornography industry |
| Media.Vision | Kōtō | March 1993 | video game industry |
| MediaKite | — | April 1991 | — |
| Medienhaus Oetinger | — | June 12, 1946 | — |
| Mega Cat Studios | Pittsburgh | 2015 | video game industry |
| Mega Enterprise | Yeongdeungpo District | 1998 | video game industry |
| MegaHouse | Tokyo | March 2, 1962 | — |
| MegArts | — | — | video game industry |
| Melonhead Games | Adelaide | 2017 | video game industry |
| Melsoft Games | Minsk | 2008 | software industry |
| Memorable Games | Turin | 2013 | video game industry |
| Meridian’93 | Luhansk | 1993 | — |
| Messenger2050 Technologies | — | 2008 | — |
| Messier Games | — | — | video game industry |
| Metacore Games | Helsinki | January 12, 2015 | video game industry |
| Metro Corporation | Yodogawa-ku | May 15, 1987 | video game industry |
| Metropolis Software | Warsaw | 1992 | video game industry |
| Micro Forté | Canberra | 1985 | video game industry |
| Micro Magic Inc. | Sunnyvale | 1995 | — |
| Micro Status | — | — | — |
| Microdeal | St Austell | — | — |
| Microfolie's | France | 1992 | video game industry |
| MicroGraphic Image | — | 1983 | video game industry |
| Microids Studio Lyon | Paris | July 20, 2021 | video game industry |
| Microids Studio Paris | Paris | September 29, 2021 | video game industry |
| Micronet | Hokkaidō, Sapporo | October 29, 1982 | video game industry |
| Micronics | — | — | video game industry |
| MicroPlay Software | — | August 1991 | — |
| MicroProse | Hunt Valley | 1982 | video game industry |
| MicroProse-Spectrum HoloByte UK-Europe | — | — | — |
| MicroStyle | — | — | — |
| MiCROViSion Inc. | Toshima | December 1986 | video game industry |
| Midas Interactive Entertainment | — | 1998 | — |
| Midway Home Entertainment | — | 1994 | — |
| Midway Studios San Diego | — | 2009 | video game industry |
| Midway Studios – Los Angeles | San Diego | 1994 | video game industry |
| Midway Studios – Newcastle | Gateshead | 1996 | — |
| Mighty Kingdom | Adelaide | 2010 | video game industry |
| Mighty Polygon | Valencia | — | — |
| Mighty Rocket Studio | Tourcoing | 1999 | video game industry |
| Mikro-Gen | Bracknell | 1981 | — |
| Milestone | Suginami | 2003 | video game industry |
| Milestone S.r.l. | Milan | 1994 | video game industry |
| Military Simulations | Vancouver | 1994 | video game industry |
| Milkstone Studios | — | — | video game industry |
| Milky Tea | — | — | — |
| Minato Soft | Japan | 2006 | video game industry |
| Mindware Studios | Prague | 2001 | video game industry |
| Miniclip | Neuchâtel | 2001 | video game industry |
| Mintrocket | — | — | video game industry |
| Mirrorsoft | London | 1982 | — |
| Mob Entertainment | — | — | video game industry |
| Mobirix | — | March 2004 | video game industry |
| Modus Games | Walnut Creek | — | video game industry |
| Mojang Studios | Stockholm | 2009 | video game industry |
| Mojiken Studio | — | 2013 | video game industry |
| Mommy's Best Games | — | 2007 | — |
| Momo-pi | Bulle | February 5, 2018 | video game industry |
| Monkey Craft | — | — | video game industry |
| Monochrome Paris | — | — | — |
| Monokel | Cologne | — | video game industry |
| Monolith Productions | Kirkland | October 25, 1994 | video game industry |
| Monomi Park | San Mateo | 2014 | video game industry |
| Monster Games | Northfield | 1996 | video game industry |
| Moon Studios | Vienna | 2010 | video game industry |
| Moonbyte Games | Neustadt an der Weinstraße | — | — |
| Mooneye Studios | Hamburg | — | video game industry |
| Mopeful Games | — | — | video game industry |
| Morteshka | Perm | May 2015 | video game industry |
| Mosaic Publishing | London | 1983 | — |
| Mother Gaia | Bauru | 2008 | video game industry |
| Motive Studio | Montreal | July 13, 2015 | video game industry |
| MR-Software GbR | — | — | — |
| MumboJumbo | — | 2001 | video game industry |
| Muse Software | Baltimore | 1978 | video game industry |
| Muzzy Lane | Newburyport | — | video game industry |
| Mynet | Tokyo | June 14, 2006 | — |
| Mystery Studio | Montevideo | 2002 | casual game |
| Mytona | Yakutsk | 2012 | video game industry |
| Mytopia | Palo Alto | 2006 | — |