| Troglobytes Games | Spain | — | 1 | 1 |
| Troika Games | United States | 1998 | 1 | — |
| Tru Blu Entertainment | Australia | 1999 | — | 13 |
| Tsunami Games | United States | 1991 | 1 | — |
| TT Fusion | United Kingdom | 2006 | 6 | — |
| TT Games | United Kingdom | 2005 | 7 | 3 |
| TT Games Publishing | United Kingdom | 2004 | — | 1 |
| Tummy Games | Serbia | — | 1 | 1 |
| Tunnel Vision Games | Denmark | 2013 | 1 | — |
| Tunnel Vision Studio | Italy | 2020 | 1 | — |
| Turbo Button | — | — | 2 | 1 |
| Turbo Tape Games | Norway | 2008 | 1 | — |
| Turn 10 Studios | United States | 2001 | 8 | — |
| TV Asahi | Japan | October 15, 2013 | — | 1 |
| Twilight Frontier | Japan | — | 11 | 8 |
| Twin Otter Studios | United States | November 14, 2020 | 1 | — |
| Twin Sails Interactive | France | — | 1 | 8 |
| Twisted Dragon Media | United States | — | 1 | 1 |
| Twisted Pixel Games | United States | 2006 | 1 | — |
| Twitch Interactive | United States | September 18, 2006 | — | 1 |
| Two Point Studios | United Kingdom | 2016 | 1 | — |
| Two Tiny Dice | France | — | 1 | — |
| Two Tribes | Netherlands | 2000 | 5 | 2 |
| Tynesoft | — | 1983 | — | 2 |
| Type‐Moon | Japan | 2003 | 7 | 2 |
| Typhoon Games | — | 2001 | — | 2 |
| U-Play Online | Spain | November 2009 | 2 | 1 |
| U.S. Gold | United Kingdom | 1984 | 1 | 19 |
| Ubisoft Abu Dhabi | — | October 2011 | 1 | — |
| Ubisoft Annecy | — | 1996 | 3 | — |
| Ubisoft Berlin | Germany | 2018 | 1 | — |
| Ubisoft Blue Byte | Germany | October 1988 | 28 | 10 |
| Ubisoft Casablanca | — | April 1998 | 1 | — |
| Ubisoft Chengdu | People's Republic of China | September 2007 | 3 | — |
| Ubisoft Ivory Tower | France | 2007 | 2 | — |
| Ubisoft Kyiv | Ukraine | 2008 | 9 | — |
| Ubisoft Leamington | United Kingdom | 2002 | 4 | — |
| Ubisoft Mainz | Germany | — | 1 | — |
| Ubisoft Milan | Italy | 1998 | 8 | — |
| Ubisoft Mumbai | India | October 2018 | 2 | — |
| Ubisoft Nagoya | Japan | September 1996 | 1 | — |
| Ubisoft Paris | France | 1986 | 33 | — |
| Ubisoft Pune | India | 2008 | 4 | — |
| Ubisoft Quebec | Canada | 2005 | 10 | — |
| Ubisoft Reflections | United Kingdom | 1984 | 15 | — |
| Ubisoft Romania | Romania | 1992 | 9 | — |
| Ubisoft San Francisco | — | 2009 | 2 | — |
| Ubisoft Shanghai | People's Republic of China | 1996 | 13 | — |
| Ubisoft Sofia | — | 2006 | 3 | — |
| Ubisoft Toronto | Canada | 2009 | 8 | — |
| UEP Systems | Japan | April 12, 1985 | 4 | — |
| UFO Interactive Games | United States | 1999 | — | 4 |
| Uken Games | Canada | 2009 | 2 | — |
| Ukiyotei | Japan | 1991 | 1 | — |
| Ullucus Heaven | Japan | 2006 | 4 | 4 |
| Ultimate Games | Poland | — | — | 17 |
| Ultimate Play the Game | United Kingdom | 1982 | — | 3 |
| Ultra Games | United States | 1988 | — | 7 |
| Ultrasoft | — | 1989 | — | 2 |
| Umbra Software | Finland | 2007 | — | — |
| Un Je Ne Sais Quoi | France | May 11, 2018 | 1 | — |
| Unalis | Taiwan | December 2, 1976 | — | 1 |
| UNBALANCE | Japan | March 18, 1998 | — | — |
| Undead Labs | United States | November 23, 2009 | 1 | — |
| Undercoders | Spain | 2005 | 2 | 1 |
| Underground Development | United States | 1994 | 3 | — |
| Unexpected Studio | France | November 2015 | 2 | 1 |
| Unique Development Studios | Sweden | 1993 | 3 | — |
| United Front Games | Canada | 2007 | 2 | — |
| United Label | Poland | — | — | 2 |
| United States Army | United States | June 14, 1775 | 2 | 1 |
| Unity Technologies | United States | August 2, 2004 | — | — |
| Universal Entertainment | Japan | 1969 | 4 | 3 |
| University of Skövde | Sweden | 1977 | 1 | 1 |
| Universomo | Finland | 2002 | 2 | — |
| Unknown Worlds Entertainment | United States | 2001 | 2 | 2 |
| Unties | Japan | — | — | 1 |
| Untold Tales | Poland | 2020 | — | 3 |
| UPL | Japan | 1972 | 2 | 2 |
| Upside Studios | Sweden | March 15, 2001 | 6 | — |
| Upstairs Digital | Denmark | September 27, 2016 | 1 | 1 |
| Upstream Arcade | United Kingdom | February 4, 2020 | 1 | — |
| Urban Games | Switzerland | 2013 | 3 | — |
| Urnique Studio | Thailand | — | 1 | 1 |
| UserJoy Technology | Taiwan | May 19, 1995 | 4 | 1 |
| Ustwo Games | — | — | 7 | 6 |
| Utopos Games | United States | — | — | 1 |
| UTV Ignition Games | United Kingdom | 2002 | — | 4 |
| Uvula | United States | — | 1 | — |
| Vaka | Japan | February 15, 2018 | 1 | 2 |
| Valcon Games | United States | 2005 | — | 2 |
| Valiant Game Studio | Sweden | 2017 | 1 | 1 |
| VALOFE | South Korea | — | — | 2 |
| Valve Corporation | United States | 1996 | 30 | 28 |
| Vanguard Entertainment | — | 2010 | 1 | — |
| Vanillaware | Japan | February 8, 2002 | 2 | — |
| Vanpool | Japan | 1999 | 5 | — |
| VAP Inc. | Japan | January 24, 1981 | 3 | 3 |
| Varie | Japan | 1986 | — | 4 |
| Vatra Games | Czech Republic | 2009 | 1 | — |