| Skyblue AnalyticsFintech | Fintech | Montevideo, Uruguay | — | skyblueanalytics.com |
| SkyflowB2B | B2B | — | — | flyskyflow.com |
| SkyglassOther | Other | Lyons, United States | — | skyglass.com |
| SkySpecsIndustrials | Industrials | Ann Arbor, United States | Danny Ellis | skyspecs.com |
| SkyWatchOther | Other | Waterloo, Canada | James Slifierz | skywatch.ai |
| SlackB2B | B2B | — | Stewart Butterfield | slack.com |
| SlangB2B | B2B | New York City, United States | Josh Reeves | slang.ai |
| SlashConsumer | Consumer | New York City, United States | — | tapslash.com |
| SlashyB2B | B2B | San Francisco, United States | | slashy.com |
| SliceFintech | Fintech | Auckland, New Zealand | — | slicetobuy.com |
| Slice of SauceOther | Other | Los Angeles, United States | Existence Sawyer | sliceofsauce.com |
| Slideflow LabsB2B | B2B | Chicago, United States | James Dolezal | slideflow.ai |
| Slingshot AerospaceOther | Other | El Segundo, United States | Melanie Stricklan | slingshot.space |
| Slope SoftwareFintech | Fintech | Gastonia, United States | David Steele | slopesoftware.com |
| SmallholdOther | Other | Brooklyn, United States | Andrew Carter | smallhold.com |
| Smart BricksB2B | B2B | Dubai, United Arab Emirates | — | smart-bricks.com |
| Smart Diagnostics SystemsOther | Other | Kansas City, United States | — | alden.tech |
| Smartbin.ioIndustrials | Industrials | Walnut, United States | — | smartbin.io |
| SmartHopB2B | B2B | Miami, United States | Guillermo Garcia | smarthop.com |
| SmartMindOther | Other | Seoul, South Korea | — | smartmind.team |
| SmiletronixOther | Other | Barcelona, Spain | — | smiletronix.com |
| SmoreOther | Other | Tel Aviv, Israel | Nimrod Kramer | smore.com |
| SmunchOther | Other | Berlin, Germany | Maximilian Reuter | smunch.co |
| snaplandB2B | B2B | Tel Aviv, Israel | — | snapland.ai |
| SnapSwapFintech | Fintech | Luxembourg, Luxembourg | — | snapswap.eu |
| SoBetConsumer | Consumer | Nashville, United States | — | sobet.io |
| SocialSign.inB2B | B2B | New York City, United States | — | socialsign.in |
| SocialthingFintech | Fintech | Boulder, United States | Ben Hanten | socialthing.com |
| Socratix AIB2B | B2B | — | | getsocratix.ai |
| SojorneConsumer | Consumer | Sandy Springs, United States | — | sojorne.com |
| Solar UnsoiledIndustrials | Industrials | Durham, United States | — | solarunsoiled.com |
| SolestialIndustrials | Industrials | Tempe, United States | Sina Golshany | solestial.com |
| Solim HealthHealthcare | Healthcare | Dover, United States | — | solimhealth.com |
| SoLo FundsFintech | Fintech | Cincinnati, United States | Travis Holoway | solofunds.com |
| SolsticeIndustrials | Industrials | Boston, United States | Steph Speirs | solstice.us |
| SolvaFintech | Fintech | — | | solvatechnology.com |
| SommosFintech | Fintech | Santa Cruz, Bolivia | — | sommosapp.com |
| SonarlyB2B | B2B | — | | sonarly.com |
| soonaOther | Other | Denver, United States | Hayley Anderson | soona.co |
| Sorair TechnologiesOther | Other | Didcot, United Kingdom | — | sorair.co.uk |
| SoranoAIOther | Other | Stanford, United States | — | sorano.co |
| SorareFintech | Fintech | — | Nicolas Julia | sorare.com |
| SorceB2B | B2B | San Francisco, United States | | sorce.jobs |
| soundchartsConsumer | Consumer | Paris, France | Alexis Rousseau | soundcharts.com |
| Source.devB2B | B2B | — | — | source.dev |
| SourcebotB2B | B2B | San Francisco, United States | | sourcebot.dev |
| Sourcery.AIB2B | B2B | London, United Kingdom | Boris Feld | sourcery.ai |
| Space RediOther | Other | Englewood, United States | — | spaceredi.com |
| SpacebackendOther | Other | Wilmington, United States | — | spacebackend.com |
| SpaceXIndustrials | Industrials | — | Elon Musk | spacex.com |