| San Francisco Museum of Modern Art | nonprofit organization, art museum, publishing house, museum, museum of modern art | San Francisco | 1935 |
| San Francisco Opera | nonprofit organization, opera company | San Francisco | 1923 |
| San Francisco Unified School District | school district in the United States | — | 1851 |
| Sanmina Corporation | business, public company | San Jose | 1980 |
| Santa Monica College | community college, college, public educational institution of the United States | Santa Monica | 1929 |
| Santa Monica Studio | video game developer | Playa Vista | 1999 |
| Sanzaru Games | video game developer | Foster City, California | 2007 |
| Saucony | business, subsidiary company | Lexington | 1898 |
| Scale AI | technology company | San Francisco | 2016 |
| Schneider's Bakery | television production company | Los Angeles | June 6, 1996 |
| Scholastic Corporation | media distributor, book publisher, business, education company, public company | New York City, Scholastic Building | 1920 |
| Schomburg Center for Research in Black Culture | library branch, creative residency, research library, public library, library building | — | 1925 |
| School of Visual Arts | private for-profit educational institution, art academy, university | New York City | 1947 |
| Schweizer Aircraft Corporation | former entity, organization, business | Horseheads, New York City | 1939 |
| Schwinn Bicycle Company | business | Chicago | 1895 |
| Scribd | online service, organization, business | San Francisco | March 2006 |
| Scripps-Booth | business, enterprise, automobile manufacturer | Detroit | 1913 |
| Scuderia Cameron Glickenhaus | automobile manufacturer | Sleepy Hollow | 2004 |
| Sears | business, public company | Hoffman Estates | 1892 |
| Seattle Central Library | library, library building | — | May 23, 2004 |
| Seattle Computer Products | business | Seattle | 1979 |
| Seattle's Best Coffee | business | Seattle | 1991 |
| SeaWorld | business, chain | Orlando | March 21, 1964 |
| SeaWorld Orlando | marine mammal park, animal theme park | — | December 15, 1973 |
| Selig Polyscope Company | film production company | Los Angeles | 1896 |
| Selznick International Pictures | film production company, film studio | Los Angeles | 1935 |
| Semrush | brand, business, public company | Boston | August 3, 2008 |
| Servant Air | airline | Kodiak | 2003 |
| Sesame Workshop | production company, nonprofit organization | 1 Lincoln Plaza, New York City | May 20, 1968 |
| Shaba Games | business | San Francisco | 1997 |
| Shimmer Women Athletes | business, enterprise | Illinois, Chicago, Berwyn | November 6, 2005 |
| Shiny Entertainment | video game developer, business | Laguna Beach, Newport Beach | 1993 |
| ShondaLand | television production company | Los Angeles | 2005 |
| Showtime | production company, film production company, cable channel, specialty channel, subscription television | New York City | July 1, 1976 |
| Shrine Auditorium and Expo Hall | auditorium, function hall, theatre building, movie theater | — | 1925 |
| Shudder | dot-com company, video streaming service | New York City | 2015 |
| Shure | business, enterprise | Niles | 1925 |
| Shuttle America | airline | Indianapolis | 1998 |
| Sierra Nevada Corporation | business | Sparks | 1963 |
| Sigma-Aldrich | business, enterprise, public company, biotechnology company | St. Louis | 1976 |
| Signetics | integrated device manufacturer | Sunnyvale | 1961 |
| Sikorsky Aircraft Corporation | aerospace manufacturer | Stratford, Connecticut | 1923 |
| Silver Airways | airline | Fort Lauderdale–Hollywood | 2011 |
| Similarweb | website, business, public company | Givatayim | 2007 |
| Simplot | business | Boise | 1929 |
| Sinclair Broadcast Group | business, enterprise, public company | Hunt Valley, Cockeysville, Union Valley | 1971 |
| Sinclair Oil Corporation | business, gas station chain | Salt Lake City | May 1, 1916 |
| Sirius Satellite Radio | former entity, business, company | New York City | May 17, 1990 |