The notions of mediation and mediatization are most often discussed in relation to politics, even though many other social phenomena, including terrorism, can be considered as mediated and mediatized. The main thesis of the paper is that contemporary terrorism is both mediated and mediatized, as citizens receive information about terrorism largely from the media, and as terrorists are guided by media logic. Terrorism and the media are commonly viewed as having a ‘symbiotic’ relationship. This relationship is manifested by the interest of terrorist groups for a greater presence in the media in order to achieve stronger media effects, and by the interest of the media for publishing news that attract public attention. In this way, the media become the main carriers of terrorist messages, but also the creators of public perception and fear of terrorism. By using the Strömbäck’s theoretical model of four phases of mediatization, the paper confirms the thesis about the existence of mediation of terrorism given that for the vast majority of Western citizens a direct and personal encounter with terrorism, especially of islamist type, is extremely rare. Therefore, it can be concluded that nowadays the media represent the most important source of information for citizens about terrorism. Furthermore, the analysis of activities of terrorist groups, particularly the IS, shows that these actors are largely guided in their actions by media logic, which is manifested through the implementation of their own media strategies with a view to manipulate and exploit the mainstream mass media. Finally, the paper confirms the existence of the mediatization of terrorism, which mainly corresponds to the Strömbäck’s third phase of mediatization.