| Script HealthHealthcare | Healthcare | Chicago, United States | — | scripthealth.co |
| Sea Machines RoboticsOther | Other | Boston, United States | Michael Johnson | sea-machines.com |
| SealutionOther | Other | Oudenaarde, Belgium | — | sealution.io |
| SeasatsOther | Other | San Diego, United States | Robert Marchese | seasats.com |
| Season ShareConsumer | Consumer | Bozeman, United States | — | seasonshare.com |
| SeatedConsumer | Consumer | New York City, United States | Bo Peabody | seated.com |
| Seated With LoveOther | Other | Ann Arbor, United States | — | seatedwithlove.com |
| Secret SkinIndustrials | Industrials | Dubai, United Arab Emirates | — | thesecretskin.com |
| Sedso.aiB2B | B2B | Singapore, Singapore | — | sedso.ai |
| Seed&SparkFintech | Fintech | Los Angeles, United States | Emily Best | seedandspark.com |
| SeedLegalsB2B | B2B | — | Anthony Rose | seedlegals.com |
| SeedsightOther | Other | — | — | seedsight.io |
| Seeing SystemsIndustrials | Industrials | — | | seeing-systems.com |
| SeekWellB2B | B2B | New York City, United States | James Donahue | seekwell.io |
| SeelFintech | Fintech | United States | Dacheng Zhao | seel.com |
| SeelFintech | Fintech | Sunnyvale, United States | Chester Ng | seel.com |
| SeeO2 EnergyIndustrials | Industrials | Calgary, Canada | — | seeo2energy.com |
| Seer AerospaceIndustrials | Industrials | New York City, United States | — | seeraerospace.com |
| sees.aiOther | Other | London, United Kingdom | — | sees.ai |
| SegmentStreamOther | Other | London, United Kingdom | Dmitry Melnikov | segmentstream.com |
| SeldonOther | Other | London, United Kingdom | Clive Cox | seldon.io |
| SelfFintech | Fintech | Austin, United States | James Garvey | self.inc |
| SelfinFintech | Fintech | San Francisco, United States | | selfin.app |
| SellRazeConsumer | Consumer | San Francisco, United States | | sellraze.com |
| Semble AIB2B | B2B | San Francisco, United States | | sembleai.com |
| SemioticB2B | B2B | San Francisco, United States | | semiotic.com |
| SendbirdConsumer | Consumer | San Mateo, United States | John S. Kim | sendbird.com |
| SendGridConsumer | Consumer | Denver, United States | Isaac Saldana | sendgrid.com |
| SenexxOther | Other | Cambridge, United States | — | senexx.com |
| Sensate RoboticsOther | Other | Los Angeles, United States | — | sensate-robotics.com |
| Sense StreetFintech | Fintech | — | — | sensestreet.com |
| SensefinityOther | Other | Lisbon, Portugal | Pedro Félix | sensefinity.com |
| SenseiOther | Other | Lisbon, Portugal | Ingrid Alongi | sensei.tech |
| SenseITB2B | B2B | Tel Aviv, Israel | — | senseit360.com |
| Sensible ObjectConsumer | Consumer | London, United Kingdom | Alex Fleetwood | sensibleobject.com |
| Senso.aiB2B | B2B | Toronto, Canada | Robb Nabb | senso.ai |
| SensytecIndustrials | Industrials | Houston, United States | — | sensytec.com |
| Sentiment SearchOther | Other | London, United Kingdom | — | sentimentsearch.com |
| SentrialB2B | B2B | — | | sentrial.com |
| SequelB2B | B2B | San Jose, United States | — | sequel.io |
| Sequence MarketsFintech | Fintech | — | | sequencemkts.com |
| SequrConsumer | Consumer | Atlanta, United States | James Segil | sequr.io |
| Serve FirstOther | Other | Epping, United Kingdom | — | servefirst.co.uk |
| Server DensityB2B | B2B | — | David Mytton | serverdensity.com |
| ServeScapeIndustrials | Industrials | Chamblee, United States | — | servescape.net |
| Servo7Industrials | Industrials | — | | servo7.com |
| SF TensorB2B | B2B | — | | sf-tensor.com |
| ShareLaTexB2B | B2B | — | John Hammersley | sharelatex.com |
| SheevaFintech | Fintech | Alexandria, United States | Nir Shmueli | sheeva.ai |
| Shelby.tvOther | Other | New York City, United States | Anjali Mullany | shelby.tv |