| Gamu ry | Finland | — | 1 | 1 |
| Ganbarion | Japan | August 13, 1999 | 8 | — |
| Gaps | Japan | 1994 | 3 | — |
| GarageGames | United States | 2000 | 6 | 20 |
| Garena | Indonesia | 2009 | — | 3 |
| Garoa Studios | Brazil | 2019 | 1 | 1 |
| Gathering of Developers | United States | 1998 | — | 19 |
| Gato Studio | Spain | 2010 | 2 | 2 |
| Gazelle | Japan | 1995 | — | — |
| GD Studio | Sweden | March 18, 2012 | 1 | — |
| Gearbox Publishing | United States | 2016 | — | 3 |
| Gearbox Software | United States | 1999 | 24 | 5 |
| Gears for Breakfast | Denmark | — | — | 1 |
| Gemdrops | Japan | — | 4 | 2 |
| General Arcade | Singapore | 2008 | 3 | — |
| General Entertainment | Japan | March 4, 1994 | 1 | — |
| General Interactive Co. | Singapore | 2016 | 2 | 2 |
| General Mills | United States | 1856 | — | 1 |
| Genius Sonority | Japan | June 2002 | 12 | 2 |
| Genki | Japan | October 16, 1990 | 20 | 5 |
| Geometric Interactive | Denmark | — | 1 | — |
| GFI Russia | Russia | 1996 | 1 | — |
| Ghost Pattern | Australia | — | 1 | 1 |
| Ghost Town Games | United Kingdom | March 6, 2015 | 2 | — |
| Ghostlight | United Kingdom | 2004 | — | 4 |
| Giant Army | United States | 2011 | 2 | 2 |
| Giant Squid | United States | 2013 | 1 | — |
| Giants Software | Switzerland | 2004 | 15 | 5 |
| Giga | Japan | July 9, 1993 | 11 | 11 |
| Giiku Games | Germany | — | — | 2 |
| Giochi Preziosi | Italy | 1978 | — | 1 |
| Givro | Japan | 1989 | 1 | — |
| Glee-Cheese Studio | France | April 2021 | 1 | — |
| Glitch | United States | 2010 | — | 2 |
| Global A Entertainment | Japan | September 12, 1997 | 3 | 3 |
| Global Star Software | United States | 1995 | — | 7 |
| Global VR | United States | 1998 | — | 1 |
| Glowfish Interactive | Belgium | — | 1 | — |
| Glu Mobile | United States | 2005 | 4 | 4 |
| GMO Gamepot | Japan | 2001 | 1 | 1 |
| GN Software | Japan | 2003 | — | 1 |
| GOAT Store | — | 2001 | — | 1 |
| Goblinz Studio | France | — | 5 | 2 |
| Goca Games | Spain | 2018 | 2 | — |
| Gogii Games | Canada | 2006 | 4 | — |
| Golden Disc Electronic | People's Republic of China | February 9, 1992 | — | 1 |
| GoldKnights | Czech Republic | — | 1 | — |
| Goloso Games | France | October 2016 | 1 | — |
| Good Gate Media | United Kingdom | 2018 | 1 | — |
| Good Shepherd Entertainment | Netherlands | 2011 | — | 10 |
| Good Smile Company | Japan | 2001 | 2 | 1 |
| Good-Feel | Japan | March 10, 2005 | 6 | — |
| Goodbye Galaxy Games | Netherlands | — | 4 | 1 |
| GoodbyeWorld Games | United States | — | 1 | — |
| Goodgame Studios | Germany | 2009 | 1 | 1 |
| Goodhustle Studios | United States | — | 2 | — |
| Google | United States | September 4, 1998 | — | 1 |
| Gorilla Systems | United States | 1995 | 1 | — |
| Got Game Entertainment | United States | — | — | 5 |
| Gotch Technology Corp. | Japan | — | 5 | — |
| Gotcha Gotcha Games | Japan | September 2020 | 5 | 22 |
| Gotham Games | United States | 2002 | — | 2 |
| Gottlieb | United States | 1997 | 1 | — |
| GrabTheGames | United States | 2012 | 4 | 36 |
| GrandMA Studios | Ukraine | 2011 | 23 | — |
| Grandslam Entertainments | United Kingdom | 1987 | — | 4 |
| Granzella | Japan | April 2011 | 4 | 3 |
| Graphic Research Co., Ltd. | Japan | May 1982 | 1 | — |
| Graphic State Games | United Kingdom | 2000 | 3 | — |
| Grasshopper Manufacture | Japan | March 30, 1998 | 9 | 1 |
| GratescaStudio | People's Republic of China | November 2, 2020 | 2 | 1 |
| Grave Danger Games | Canada | — | 1 | — |
| Gravity Corporation | South Korea | 2000 | 2 | 2 |
| Gravity Game Arise | Japan | July 2019 | — | 2 |
| Gray Matter Inc. | Canada | 1985 | 2 | — |
| Great Detail Ltd | United Kingdom | — | 2 | — |
| Green Sauce Games | Brazil | 2008 | 4 | 3 |
| Gremlin Interactive | United Kingdom | 1984 | 15 | 12 |
| Grendel Games | Netherlands | 2005 | 1 | 1 |
| Grey Alien Games | United Kingdom | 2004 | 3 | 21 |
| Grezzo | Japan | December 2006 | 10 | — |
| Grimbart Tales | Germany | 2015 | 1 | — |
| Grin | Sweden | 1997 | 2 | — |
| Griptonite Games | United States | 1994 | 14 | — |
| Gro Play | Sweden | June 12, 2012 | 1 | — |
| Grolier | United States | 1895 | — | 1 |
| Groove Games | Canada | 2001 | — | 3 |
| GROOVER | Japan | — | 1 | 1 |
| Ground Shatter | United Kingdom | May 23, 2014 | 3 | 1 |
| Grounding | Japan | September 7, 2007 | 3 | — |
| Groundspeak | — | September 2000 | 1 | 1 |
| Group SNE | Japan | 1987 | 1 | — |
| Grumpyface Studios | United States | — | 4 | — |
| Grupo Televisa | Mexico | January 8, 1973 | — | 2 |
| Gryph Frontier | Singapore | May 9, 2022 | — | 1 |
| GSC Game World | Ukraine | 2014 | 12 | 8 |
| Guard Crush Games | Canada | 2009 | 2 | 1 |
| Guerrilla Cambridge | United Kingdom | 1997 | 7 | — |
| Guerrilla Games | Netherlands | 2000 | 7 | — |
| Gumi Inc. | Japan | June 13, 2007 | 1 | 1 |