| Thin Chen Enterprise | Taiwan | 1988 | 1 | 1 |
| Think Garage | Japan | 2005 | 1 | — |
| Thinking Rabbit | Japan | 1982 | 2 | — |
| THQ | United States | April 1990 | 9 | 151 |
| THQ Digital Studios UK | United Kingdom | 2003 | 3 | — |
| THQ Nordic | Austria | 2011 | 5 | 57 |
| THQ Nordic Mobile | Germany | 2000 | 6 | 15 |
| THQ Studio Australia | — | 2003 | 1 | — |
| THQ Wireless | United States | — | 1 | 2 |
| Three Fields Entertainment | United Kingdom | 2014 | 2 | 1 |
| Three Rings | Japan | October 19, 2010 | 3 | — |
| Three-Sixty Pacific | United States | 1987 | 2 | 2 |
| Throwback Entertainment | — | 2004 | — | 2 |
| Thunderful | Sweden | 2017 | — | 16 |
| Thunderful Development | Sweden | December 13, 2017 | 1 | — |
| Thylacine Studios | — | 2014 | 4 | — |
| Tiertex Design Studios | United Kingdom | 1987 | 5 | — |
| TiGames | People's Republic of China | — | 2 | 1 |
| Tiger Electronics | United States | 1978 | 1 | — |
| Tigon Studios | United States | 2002 | — | 1 |
| TikGames | United States | 2002 | 1 | 1 |
| Tilted Mill Entertainment | United States | 2001 | 3 | — |
| Time Galleon | Brazil | 2020 | — | 2 |
| Time Warner Interactive | United States | 1993 | 1 | 1 |
| Time Warner Interactive Ltd. | United Kingdom | September 23, 1988 | 1 | 1 |
| TimeGate Studios | United States | 1998 | 3 | 1 |
| Timelock Studio | — | 2022 | 2 | — |
| TiMi Studio Group | People's Republic of China | October 9, 2014 | 3 | — |
| Tin Can Studio | France | July 20, 2019 | 1 | 1 |
| Tindalos Interactive | France | May 5, 2010 | 2 | — |
| Tinimations | Norway | 2013 | 2 | 1 |
| Tiny Bull Studios | — | 2011 | 2 | — |
| Tinymoon | Spain | — | 1 | — |
| Titus Interactive | France | 1985 | 6 | 10 |
| TKO Software | United States | 2002 | 1 | — |
| TML Studios | Germany | 2004 | 9 | 2 |
| TNX | Japan | October 6, 2006 | 2 | — |
| Toaplan | Japan | 1984 | 21 | 7 |
| Toca Boca | Sweden | 2010 | 1 | 1 |
| Toei Animation | Japan | January 23, 1948 | — | 1 |
| ToeJam & Earl Productions | United States | 1989 | 3 | — |
| Toge Productions | Indonesia | January 20, 2009 | 5 | 11 |
| Toho | Japan | August 8, 1932 | 3 | 10 |
| Tokai Communications | Japan | March 18, 1977 | 1 | 1 |
| Tokuma Shoten | Japan | March 19, 1954 | — | 2 |
| Tom Create | Japan | October 1989 | 2 | 2 |
| Tomcat System | Japan | March 6, 1991 | 1 | — |
| Tommo Inc. | United States | 1989 | — | 2 |
| Tomy | Japan | March 2006 | 3 | 16 |
| Tonic Games | Denmark | November 3, 2005 | 1 | — |
| Tonkin House | Japan | 1988 | 2 | 6 |
| Top Hat Studios | United States | — | — | 14 |
| Toplitz Productions | Austria | — | — | 7 |
| Toppluva | Sweden | 2017 | 2 | — |
| TopWare Interactive | Germany | 1995 | 3 | 5 |
| Torn Banner Studios | Canada | 2011 | 1 | — |
| Tortuga Team | Russia | — | 3 | 3 |
| Torus Games | Australia | 1994 | 10 | — |
| Tose Co. | Japan | November 1979 | 59 | — |
| Toshiba EMI Ltd. | Japan | October 1973 | — | 1 |
| Total Mayhem Games | Netherlands | — | 4 | 4 |
| Totally Games | United States | 1984 | 16 | — |
| Touchstone Pictures | United States | February 15, 1984 | — | 1 |
| Towa Chiki | Japan | May 2, 1986 | — | 1 |
| Towa Chiki | Japan | 1986 | — | 1 |
| Toybox Inc. | Japan | August 10, 2011 | 2 | — |
| Toylogic | Japan | December 2006 | 2 | — |
| Toys for Bob | United States | 1989 | 14 | — |
| Tradewest | United States | 1986 | — | 9 |
| Trainwreck Labs | Canada | — | 3 | 3 |
| Transhuman Design | Poland | — | 1 | 1 |
| Translimit | Japan | — | 1 | 1 |
| Transmission Games | — | 1996 | 3 | — |
| Transposia | Belgium | 1994 | — | 5 |
| Trashmasters | Russia | — | 1 | — |
| Traveller's Tales | United Kingdom | 1989 | 29 | — |
| Treasure | Japan | June 19, 1992 | 9 | — |
| Treco | Japan | — | — | 2 |
| TREVA Entertainment | Germany | 2006 | — | 2 |
| Treyarch | United States | 1996 | 15 | — |
| Tri Synergy | United States | 1996 | — | 3 |
| Tri-Ace | Japan | March 16, 1995 | 12 | — |
| Tri-Crescendo | Japan | February 1999 | 3 | — |
| Triangle Factory | Belgium | January 25, 2010 | 2 | 2 |
| Triangle Studios | Netherlands | 2005 | 4 | — |
| Triband | Denmark | — | 3 | 2 |
| Tribe Games | United States | 2009 | 1 | — |
| Tribetoy | United States | 2008 | 1 | 1 |
| TriBit Studio | Italy | — | 1 | — |
| Tribute Games | Canada | 2011 | — | 1 |
| Triffix Entertainment | — | 1991 | 1 | — |
| Trine Game Studios | India | — | 1 | — |
| Trine Games | India | 2006 | 2 | — |
| Trinity Team | Italy | — | 1 | — |
| Trion Worlds | United States | January 10, 2005 | 1 | 1 |
| Triple Topping | Denmark | — | 2 | 2 |
| Triple.B.Titles | United States | — | 1 | — |
| Tripwire Interactive | United States | 2005 | 3 | 4 |
| Triskell Interactive | France | September 2014 | 3 | 2 |
| Triumph Studios | Netherlands | 1997 | 12 | 1 |