| SFT Computers | |
| Sgiti | Pomeranian |
| SGPR.TECH | |
| Shape.Care Sp. z o.o. | |
| Shapespark Sp. z o.o. | |
| ShareSpace | |
| Sharp Electronics CEE | Masovian |
| ShelfWise Sp. z o.o. | |
| Shift-Systemy Komputerowe Sp. J. | Lesser Poland |
| Shoper S.A. | Lesser Poland |
| Shoplo Sp. z o.o. | Masovian |
| Si-Consulting Sp. z o.o. | Lower Silesian |
| Sidnet Solutions Sp. z o.o. | |
| Sieć Badawcza Łukasiewicz - Instytut Techniki i Aparatury Medycznej | |
| Sieć Badawcza Łukasiewicz - Poznański Instytut Technologiczny | |
| Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów PIAP | |
| Sieci Blokowe | Świętokrzyskie |
| SIETOM Sp. z o.o. | Pomeranian |
| Sii Sp. z o.o. | |
| Silk Data Sp. z o.o. | |
| Silk Software House Sp. z o.o. | Masovian |
| Silnet Media | |
| Siltec Sp. z o.o. | Masovian |
| simpl.rent | |
| Simple S.A. | Masovian |
| SimpleLocalize | |
| Sinterit Sp. z o.o. | |
| Sintra | |
| SIRC Sp z o.o. | |
| SIRTEL Sp. z o.o. | Masovian |
| SISCO Sp. z o.o. | Łódź |
| Siteimpulse | Masovian |
| SK Technologie Sp. z o.o. | |
| Skassa PL | Lublin |
| Skillforce.pl Sp. z o.o. | Silesian |
| SKK S.A. | |
| Skriware S.A. | |
| SkryBot | Masovian |
| Skyblu | |
| Skynet.net.pl | |
| Skyrise.tech | Silesian |
| SL-NET | Subcarpathian |
| Śląska Wyższa Szkoła Medyczna w Katowicach | |
| Slican Sp. z o.o. | Kuyavian-Pomeranian |
| Sloboda Studio | |
| Smablo Sp. z o.o. | |
| Smart Agro Sp. z o.o. | |
| Smart Education | |
| Smart Faktor S.A. | |
| Smart Mobile House | |