| J.P ROOM Inc | Japan | August 29, 2001 | 1 | — |
| Jackbox Games | United States | 2008 | 15 | 13 |
| Jadestone Group | Sweden | 1999 | 1 | 1 |
| Jagex | United Kingdom | 2001 | 6 | 6 |
| Jaibo Games | Ukraine | 2007 | 3 | — |
| Jakks Pacific | United States | 1995 | 1 | 1 |
| Jaleco | Japan | July 3, 2006 | 12 | 29 |
| Jaleco USA | United States | 1988 | — | 1 |
| Jam City | — | 2010 | 1 | — |
| JAM Productions | United States | 1993 | 1 | — |
| JanduSoft | Spain | 2012 | 2 | 27 |
| Japan Art Media | Japan | November 9, 1989 | 3 | — |
| Japan Media Programming Inc. | Japan | — | 1 | — |
| Japan Studio | Japan | November 16, 1993 | 17 | 3 |
| JAST USA | United States | 1997 | — | 16 |
| Javaground | United States | 2001 | 1 | — |
| Jellyfish | Japan | — | 1 | 1 |
| Jellyvision | United States | 1989 | 1 | — |
| Jester Interactive | United Kingdom | 1997 | 1 | — |
| Jet Black Games | Canada | 2007 | 1 | — |
| Jetdogs Studios | Finland | 2015 | 32 | 31 |
| Jinthree Studio | South Korea | — | 1 | 1 |
| JM Neto Game Dev | Brazil | — | 2 | 2 |
| Joindots | Germany | — | 4 | 6 |
| Jolt Online Gaming | — | 1999 | 1 | — |
| Journey Bound Games | Canada | — | 1 | 1 |
| JoWooD Ebensee | Austria | — | 1 | — |
| JoWooD Entertainment | Austria | 1995 | 5 | 24 |
| JRC Czech | Czech Republic | August 5, 2003 | — | 2 |
| Juggler Games | Poland | 2015 | 2 | — |
| Jumpship | United Kingdom | January 19, 2017 | 1 | 1 |
| Junction Point Studios | United States | 2005 | 2 | — |
| Jundroo | United States | — | 2 | 2 |
| Jupiter | Japan | June 11, 1992 | 34 | 24 |
| Just Add Water | United Kingdom | 2006 | 1 | — |
| Just for Games | France | January 12, 2011 | — | 4 |
| Jutsu Games | Poland | — | 3 | — |
| JV Games | United States | 1994 | 1 | — |
| JVC | Japan | September 13, 1927 | 1 | 4 |