| SoundsOfThings S.r.l. | South Tyrol |
| Sourcesense S.p.A. | Rome |
| SP Automazione s.n.c. | Lecco |
| Space S.p.A. | Prato |
| SparkFabrik | Milan |
| Spazio Elabora | Milan |
| SpazioDati S.r.l. | Trento |
| SPEA S.p.A. | Turin |
| Specialvideo | Bologna |
| SPIAL S.p.A. | |
| Spider 4 Web S.r.l. | Friuli-Venezia Giulia |
| Spider Electronics | Turin |
| Spin | |
| Splitty Pay S.r.l. | Milan |
| Sport e salute S.p.A. | |
| SportClubby S.r.l. | Turin |
| SpotOptics S.r.l. | Padua |
| Sprama Game Labs S.r.l. | Cagliari |
| SPS S.r.l. | Bologna |
| Spusu Italia S.r.l. | Milan |
| Sputnix.it | Palermo |
| Squized Internet Solutions | Barletta-Andria-Trani |
| Stacec S.r.l. | Reggio Calabria |
| Stal S.n.c. | Rome |
| Stam S.r.l. | Genoa |
| Star Capital SGR S.p.A. | |
| Star Tech Ventures | |
| STAR7 S.p.A. | |
| Starsoftware Group | Venice |
| Startalia S.r.l. | Rome |
| Startup Bakery S.r.l. | |
| Startup Business | Milan |
| Startup Club | Bari |
| Startup Geeks | Mantua |
| Startup Network S.r.l. | |
| StartUP.News.it | Milan |
| StartupGym Studio S.r.l. | |
| StartupItalia Open Summit | Cagliari |
| StartupItalia S.r.l. | Milan |
| Ste S.r.l. | Milan |
| Stelda Informatica S.r.l. | Como |
| Stellantis Financial Services Italia | |
| Stellar Recupero Dati | Milan |
| Steltronic S.p.A. | Brescia |
| Stelvio S.p.A. | Lecco |
| StemGen S.p.A. | |
| STEP 4 Business | Milan |
| Step Venture | |
| StephenSoftware S.r.l. | Rome |
| Stetel S.r.l. | Livorno |