| Silicon Studio | Japan | November 22, 1999 | 3 | — |
| Silky's | Japan | — | 4 | 4 |
| Silmarils | France | October 16, 1987 | 4 | 4 |
| Silver Bullet | Japan | — | — | 1 |
| Silver Style Entertainment | Germany | 1993 | 2 | — |
| Silverball Studios | United Kingdom | 2002 | 2 | — |
| SilverStarJapan Co., Ltd. | Japan | June 11, 1997 | — | — |
| SimBin | Sweden | 2003 | 2 | 1 |
| Simon & Schuster | United States | 1924 | 7 | 4 |
| Simrail S.A. | Poland | — | 1 | — |
| SIMS Co., Ltd. | Japan | June 12, 1991 | 6 | 1 |
| Simteract | Poland | — | 1 | — |
| Simtex | — | 1988 | 2 | — |
| Simutronics | United States | 1987 | 3 | 1 |
| SingleTrac | United States | 1995 | 3 | — |
| Sir-Tech | United States | 1979 | 10 | 10 |
| Sirlin Games | United States | 2005 | 1 | 1 |
| Sistema Brasileiro de Televisão | Brazil | August 19, 1981 | — | 1 |
| SITER SKAIN | Japan | — | 2 | — |
| Sixteen Tons Entertainment | Germany | 1998 | 2 | — |
| Size Five Games | United Kingdom | 2008 | 1 | 1 |
| Ska Studios | United States | 2001 | 2 | — |
| Skeleton Crew Studio | Japan | — | 1 | — |
| Skip Ltd. | Japan | July 2000 | 10 | — |
| Skipmore | Japan | — | 1 | — |
| Skitso Productions | Finland | 1995 | 2 | 1 |
| Skunkape Interactive | United States | — | 1 | — |
| Sky Bear Games | New Zealand | — | 1 | — |
| Sky Machine Studios | Australia | — | 1 | — |
| Skybound Entertainment | United States | 1992 | 1 | — |
| Skybound Games | United States | — | 1 | 6 |
| SkyBox Labs | Canada | 2011 | 3 | — |
| Skydance Media | United States | 2006 | 1 | 1 |
| Skydance TV | — | June 25, 1984 | — | 1 |
| SkyFallen Entertainment | Russia | 2002 | 2 | — |
| SkyTale Software GmbH | Austria | — | 1 | — |
| Slant Six Games | Canada | 2005 | 4 | — |
| Sledgehammer Games | United States | 2009 | 6 | 1 |
| SleepTeam | Czech Republic | 1996 | 2 | 2 |
| Slightly Mad Studios | United Kingdom | 2009 | 5 | 1 |
| Slipgate Ironworks | Denmark | 2010 | 2 | — |
| Slitherine Software UK Limited | United Kingdom | 2000 | 9 | 70 |
| Sloclap | France | May 2015 | 1 | 1 |
| Sluggerfly | Germany | — | 1 | — |
| Smack Down Productions | France | 2005 | 2 | — |
| Small Giant Games | Finland | 2013 | 1 | 1 |
| Smart Tale | France | — | 2 | — |
| Smartmelon Games | People's Republic of China | — | 1 | 1 |
| Smash House Games | United States | 2017 | 1 | 1 |
| SMEE | Japan | — | 1 | 1 |
| SMG Studio | Australia | July 2013 | 5 | 2 |
| SmileBoom | Japan | January 15, 2008 | 1 | 1 |
| Smilegate | South Korea | June 11, 2002 | 4 | 4 |
| Smoking Car Productions | United States | 1993 | 1 | — |
| Smoking Gun Interactive | Canada | 2007 | 3 | — |
| Smug Marmot Studios | United States | — | 1 | 1 |
| Snail | People's Republic of China | October 2000 | 2 | 1 |
| SneakyBox | Lithuania | — | 8 | 1 |
| Sniper Studios | United States | 2006 | 1 | — |
| SNK | Japan | December 2016 | 55 | 51 |
| SNK | Japan | April 1986 | 17 | 38 |
| SNK-Games | Russia | 2003 | 3 | — |
| Snoozy Kazoo | United States | May 2020 | 2 | — |
| Snow Cannon Games | Norway | — | — | 1 |
| Snowball Studios | Russia | 1996 | — | 2 |
| Snowblind Studios | United States | 1997 | 3 | — |
| Snowcastle Games | Norway | — | 3 | 2 |
| Snowman | Canada | 2012 | 4 | 2 |
| So Romantic | Taiwan | 2012 | 2 | — |
| Soaphog Game Studio | Latvia | 2016 | 1 | 1 |
| Social Democratic Party of Germany | Germany | May 23, 1863 | — | 1 |
| Soedesco | Netherlands | 2001 | — | 13 |
| Soft Leaf Studios | United Kingdom | 2019 | 1 | — |
| Soft-World International | Taiwan | 1983 | — | — |
| Softclub | Russia | 1994 | 1 | 17 |
| Softdisk | United States | 1981 | 3 | 5 |
| Softgold Computerspiele | Germany | 1986 | — | 3 |
| Softhouse Chara | Japan | 2000 | 8 | 8 |
| Softhouse-seal | Japan | 2009 | 1 | 2 |
| SoftLab-NSK | Russia | 1988 | — | — |
| Softmax | South Korea | October 28, 1994 | 2 | — |
| Softstar Entertainment | Taiwan | April 27, 1988 | 9 | 9 |
| Softstar Technology (Shanghai) Co., Ltd. | People's Republic of China | June 14, 2001 | 2 | — |
| Software 2000 | Germany | 1987 | 3 | 3 |
| Software Creations | United Kingdom | 1985 | 10 | — |
| Software Creations | United States | — | — | 1 |
| Software Projects | United Kingdom | 1983 | 1 | 2 |
| Sokaikan | United Kingdom | September 18, 2017 | 1 | — |
| Sokpop Collective | Netherlands | 2015 | 98 | 97 |
| Sold-Out Software | United Kingdom | 1997 | 1 | 5 |
| Soleil | Japan | August 2008 | 2 | — |
| SomaSim | United States | 2013 | 2 | — |
| Somethin' Else Sound Directions Ltd. | United Kingdom | 1991 | 1 | — |
| Sometimes You | Russia | — | 4 | 28 |
| SomniumSoft | Italy | — | — | 1 |
| Sonalysts (United States) | United States | 1973 | 1 | 1 |
| Sonic Powered | Japan | April 1998 | 2 | — |
| Sonic Team | Japan | 2000 | 74 | — |
| Sonka | Poland | — | 1 | — |
| Sonnori | South Korea | February 1998 | 1 | 1 |