| SeFlow.Net | Lodi |
| Selco Industry S.p.A. | Bologna |
| Selcom Group S.p.A. | Bologna |
| Sellalab | Biella |
| Sellf S.r.l. | |
| Selt-Inform S.r.l. | Piacenza |
| SELTA S.p.A. | Milan |
| Semantic S.r.l. | Bergamo |
| Sembox S.r.l. | Milan |
| SemShop | Rieti |
| Seneca S.r.l. | Padua |
| Sens-in | Bologna |
| Sensible Data | Rome |
| Sensoworks S.r.l. | |
| Sentinel Diagnostics | Milan |
| SEO Leader | Milan |
| SEO Sito Web | Turin |
| SEO Tester Online | Catania |
| SEO Utility | Rome |
| SEORaffaello | Bologna |
| Seowebbs S.r.l. | Lecce |
| SEOZoom | Naples |
| Sequel S.r.l. | Milan |
| Sequency | Milan |
| Serenis Health S.r.l. | |
| Serigroup S.r.l. | Belluno |
| Serinn S.n.c. | Milan |
| SERP S.r.l. | Turin |
| Sertec S.r.l. | Verona |
| Sertori S.p.A. | Milan |
| Server24.it | South Tyrol |
| Serverplan S.r.l. | Frosinone |
| ServiTecno S.r.l. | Milan |
| Servitly S.r.l. | |
| ServizioFTP.com | Varese |
| SeSa S.p.A. | |
| SETIS S.r.l. | Milan |
| Sfera Networks S.r.l. | Bergamo |
| Sferyx S.r.l. | Milan |
| SGS S.r.l. | Agrigento |
| ShargeMe EVs Blog | Friuli-Venezia Giulia |
| Sharp Electronics (Italia) S.p.A. | Milan |
| Shellrent S.r.l. | Vicenza |
| Shield S.r.l. | Novara |
| Shift S.r.l. | Como |
| Shiny S.r.l. | Milan |
| ShopFully S.p.A. | |
| ShoppyDoo | Pavia |
| Shorr Kan S.r.l. | Turin |
| SHOW.IT S.r.l. | Turin |