| IBA Group, a.s. | Prague |
| IceWarp | Prague |
| ICP, spol. s r.o. | Central Bohemian |
| ICT UNIE o.s. | Prague |
| iDevBand | |
| Idiada CZ, a.s. | Hradec Králové |
| IdStory | |
| Igloonet | |
| Ignum | Prague |
| Iguassu Software Systems | |
| Ika Data, spol. s r.o. | |
| iKFSystems | Prague |
| Image Studio, s.r.o. | |
| ImageWalker | Prague |
| IMFsoft, s.r.o. | Moravian-Silesian |
| IMP net, s.r.o. | |
| Impact Hub Brno | |
| Impact Hub Česká Republika | |
| Impact Hub Ostrava | |
| Impact Hub Praha | Prague |
| Impact Hub Zlín | |
| IMPROMAT CZ, spol. s.r.o. | Prague |
| Improvisio Software, s.r.o. | Prague |
| Impulse Ventures | |
| In creative | |
| Incomaker | Prague |
| inCUBE Interactive, s.r.o. | |
| Industra | |
| iNET Solutions, s.r.o. | Prague |
| Inexes, s.r.o. | Prague |
| Infocity Hosting | Moravian-Silesian |
| INFONIA spol. s r.o. | Prague |
| Informica | Prague |
| InfoTech-Cs | South Moravian |
| Ing. Ondřej Bým - ONIT | Liberec |
| Ing. Petr Falek, Engineering Service | South Bohemian |
| InstaCover | |
| Institute of Information Theory and Automation | Prague |
| Institute of Information Theory and Automation, Czech Academy of Sciences | |
| Institute of Mathematics of the Czech Academy of Sciences | Prague |
| Institute of Scientific Instruments of the Czech Academy of Sciences | |
| Integsoft, s.r.o. | |
| INTELEK.CZ, s.r.o. | |
| Intelligent Trading Foundation | |
| Intencio, s.r.o. | South Moravian |
| Intercodec Czech, s.r.o. | |
| InterEco services, s.r.o. | |
| International Business Forum | |
| Internet Info, s.r.o. | |
| Internet Pb, spol. s r.o. | Prague |