| Safari Games | Japan | — | 2 | — |
| Saffire | United States | 1993 | 3 | — |
| Saga Planets | Japan | — | 5 | 4 |
| Sakari Games | Belgium | — | 3 | 3 |
| Sakata SAS Co., Ltd. | Japan | 1985 | 2 | — |
| SakeVisual | United States | 2009 | 4 | 3 |
| SakuraGame | People's Republic of China | — | — | 6 |
| Sammy Corporation | Japan | November 1975 | — | 12 |
| Samsung Electronics | South Korea | January 13, 1969 | — | 2 |
| Samurai Punk | Australia | — | 3 | 2 |
| San Diego Studio | United States | 2001 | 20 | — |
| Sand Castles Studio | Spain | November 2019 | 1 | — |
| Sandlot | Japan | March 12, 2001 | 7 | — |
| Sandlot Games | United States | 2002 | 5 | 4 |
| Sanrio | Japan | August 10, 1960 | 2 | — |
| Sanritsu Denki | Japan | — | 2 | — |
| Santa Entertainment | Japan | 1997 | 1 | — |
| Santa Monica Studio | United States | 1999 | 5 | — |
| Santa Ragione | Italy | June 21, 2010 | 1 | 2 |
| Sanuk Games | Thailand | 2003 | 6 | — |
| Sanyo | Japan | February 1947 | 1 | — |
| Sanzaru Games | United States | 2007 | 12 | — |
| Saona Studios | Spain | — | 1 | — |
| Sapphire Dragon Productions | Australia | — | 3 | 3 |
| Sarbakan | Canada | 1998 | 1 | — |
| Sassybot | Netherlands | — | 1 | 1 |
| SAT-BOX | Japan | — | 3 | 3 |
| Saturn-plus | — | 1997 | 12 | — |
| Savage Entertainment | United States | 1997 | 1 | — |
| Scavengers Studio | Canada | — | 1 | 1 |
| SCE Studio Liverpool | United Kingdom | 1984 | 13 | 16 |
| Schell Games | United States | 2002 | 8 | 7 |
| Schmidt Spiele | Germany | 1907 | — | — |
| Scholastic Corporation | United States | 1920 | 1 | 2 |
| Scitron & Art Inc. | Japan | 1988 | 2 | — |
| Scopely | United States | 2011 | 1 | — |
| Screenlife Games | United States | 2002 | 1 | 1 |
| Scriptwelder Studio | Poland | — | 14 | 1 |
| SCS Software | Czech Republic | 1997 | 18 | 4 |
| Sculptured Software | United States | 1984 | 7 | — |
| Scythe Dev Team | United States | 2017 | 1 | — |
| SeaCorpTech | United Kingdom | — | 1 | 1 |
| Seasun | People's Republic of China | 1995 | 4 | 3 |
| Seaven Studio | France | February 25, 2013 | 1 | 2 |
| Second Dinner | United States | April 2018 | 1 | — |
| Second Maze | Netherlands | — | — | 2 |
| Secret Mode | United Kingdom | September 29, 2020 | — | 7 |
| Sega AM2 | Japan | October 1983 | 31 | — |
| Sega Amusement | Japan | November 26, 1971 | 1 | — |
| SEGA Europe | United Kingdom | 1986 | — | 2 |
| Sega Fave | Japan | April 1998 | — | 1 |
| Sega Interactive | Japan | April 2015 | 1 | 3 |
| Sega of America | United States | March 10, 1986 | — | 2 |
| Sega Racing Studio | United Kingdom | 2005 | 1 | — |
| Sega Sammy Holdings | Japan | October 2004 | — | 3 |
| Sega Sports R&D | Japan | 1994 | 12 | — |
| SEGA Studios Australia | Australia | July 2002 | 1 | — |
| Sega Studios San Francisco | United States | 1999 | 3 | — |
| Sega Technical Institute | United States | 1991 | — | — |
| Sega Wow | Japan | 2003 | 18 | — |
| SegaSoft | United States | 1995 | 1 | — |
| Seibu Kaihatsu | Japan | 1982 | 8 | 5 |
| Sekai Project | United States | 2007 | 1 | 109 |
| Sengi Games | Ukraine | 2018 | 1 | — |
| Senile Team | Netherlands | 2003 | 1 | — |
| Sennari Games | United States | July 2000 | 1 | — |
| Sensible Software | United Kingdom | 1986 | 3 | — |
| Sensory Sweep Studios | United States | 2003 | 3 | — |
| Sente Technologies | — | 1982 | 1 | — |
| Seriously | Finland | 2013 | 1 | 1 |
| SETA Corporation | Japan | October 1985 | 3 | — |
| SFB Games | United Kingdom | September 2, 2002 | 3 | 2 |
| Shaba Games | United States | 1997 | 3 | — |
| Shall Luck Plus | Japan | 2002 | — | 1 |
| Sharkmob | Sweden | 2016 | 1 | 1 |
| Shift | Japan | June 1999 | 3 | — |
| Shift Up | South Korea | December 2, 2013 | 1 | — |
| Shin'en Multimedia | Germany | 1999 | 2 | 2 |
| Shiny Entertainment | United States | 1993 | 4 | — |
| Shiny Shoe | United States | 2011 | 1 | — |
| Shiravune | Japan | 2019 | — | 16 |
| Shiro Games | France | October 2012 | 2 | 2 |
| Shiver Entertainment | United States | 2012 | 1 | — |
| Shiver Games | Finland | 2010 | 3 | 3 |
| Shochiku | Japan | 1895 | — | 1 |
| Shockwave | United States | — | — | 1 |
| Shoeisha | Japan | 2006 | — | 1 |
| Shogakukan-Shueisha Productions | Japan | June 26, 1967 | 1 | 2 |
| Shrapnel Games | United States | 1999 | — | 4 |
| Shueisha Games | Japan | February 16, 2022 | — | 2 |
| Sickhead Games | United States | October 2002 | 1 | — |
| Sidhe | New Zealand | 1997 | 7 | — |
| Siemens Nixdorf Informationssysteme | Germany | October 1990 | — | 1 |
| Sierra Europe | United Kingdom | — | — | 1 |
| Sierra On-Line | United States | 1979 | — | 4 |
| Siesta | Japan | — | 1 | 1 |
| Signal Studios | United States | 2009 | 1 | — |
| Silesia Games | Poland | — | — | 6 |
| Silicon Dreams Studios | United Kingdom | March 1994 | 7 | — |
| Silicon Knights | Canada | 1992 | 2 | — |