| JavaStart | Lower Silesian |
| JAWO-Projekt Sp. z o.o. | Masovian |
| Jazzy Innovations Sp. z o.o. | |
| JBR | Silesian |
| JCHost.pl | Lesser Poland |
| JCommerce Sp. z o.o. | Silesian |
| Jednostki Innowacyjno-Wdrożeniowe Profile Sp. z o.o. | Lower Silesian |
| JetStyle | |
| Jetstyle Sp. z o.o. | |
| Jezierski.IT | Lesser Poland |
| JJP Biologics | |
| JM elektronik Sp. z o.o. | Silesian |
| JMC, LLC | Masovian |
| JMK Computer Sp. z o.o. | Masovian |
| JMMJ | Masovian |
| JMR | |
| Jobs.pl S.A. | |
| Joomla.pl | Masovian |
| JPConsulting.pl | |
| JSystems | |
| JT-Soft | Kuyavian-Pomeranian |
| Jujubee S.A. | Silesian |
| Junisoftex Sp. z o.o. | |
| jurXpert | Masovian |
| Jutro Medical Sp. z o.o. | |
| JW Web Development | Kuyavian-Pomeranian |
| K2 Holding S.A. | Masovian |
| Kaban Tool | |
| Kaczka Studio | Silesian |
| Kalasoft | Greater Poland |
| Kamee Sp. z o.o. | Lesser Poland |
| Kamilnotebook | Lower Silesian |
| Kangur Electronics | |
| Kantata Sp. z o.o. | Kuyavian-Pomeranian |
| Kantor Bitcoin | |
| Kantor.pl | |
| Karkonoska Akademia Nauk Stosowanych | |
| Kaszubsko-Pomorska Szkoła Wyższa w Wejherowie | |
| Katedra Informatyki i Automatyki | Subcarpathian |
| KateOS | Łódź |
| Katowicka Specjalna Strefa Ekonomiczna | |
| KCR S.A. | |
| KDS | Silesian |
| Kedar | Pomeranian |
| Kempa Satellite Networks | Masovian |
| Kielecki Park Technologiczny | |
| KIM Group | Lesser Poland |
| Kingweb | Lesser Poland |
| KISS digital Sp. z o.o. | |
| Kiwee Sp. z o.o. Sp.k. | Lower Silesian |