| Siru Mobile | |
| Sitebuilders Finland Oy | Uusimaa |
| Skandal Technologies | Uusimaa |
| SkenarioLabs Oy | |
| Skycode | |
| Skyfora | |
| Slap Media | Uusimaa |
| Slush | Uusimaa |
| Small Giant Games | Uusimaa |
| Smartbi | |
| Smartblock Oy | |
| Smartcom Labs | |
| Smartifik Oy | |
| Smartly.io Solutions Oy | |
| Smartpaper | |
| Smartvatten Oy | |
| Smoothly Oy | |
| Snapshop | |
| Sniffie Software Ltd | |
| Sofor Oy | South Ostrobothnia |
| Softability | Uusimaa |
| Softagram Oy | |
| Softman Oy | Ostrobothnia |
| Software Explosion Oy | Central Finland |
| Software Finland ry | |
| Solar Foods Oy | |
| Solar Water Solutions Oy Ltd | |
| Solita | Uusimaa |
| Solteq | Uusimaa |
| Soma Pilvi | Kymenlaakso |
| Spacent | |
| Sparkmind.vc | |
| Specim, Spectral Imaging Ltd | |
| Spectarium Games | |
| Speechly | Uusimaa |
| Speechly | |
| SQ Consulting Oy | Pirkanmaa |
| SS Datapalvelu Oy | South Ostrobothnia |
| SSH Communications Security | |
| StageZero Technologies | |
| Starttaamo | |
| Startup Commons | Uusimaa |
| Startup Finland ry | |
| Startup-säätiö | Uusimaa |
| Startup100 | |
| Statrup Sauna | Uusimaa |
| Statzon | |
| StealthCase Oy | |
| Steerpath Oy | |
| Straightforward Capital | Uusimaa |