This thesis is intended to approach the phenomenon of online radicalisation from an unconventional point of view: communication. As many believe, online radicalisation is something uniquely related to the dynamics of terrorism and as such must be exclusively approached from a legal point of view; however, this study will demonstrate that the phenomenon is far more complex and involves the sum of a multitude of different behaviours that must be approached and analysed from different perspectives, while never underestimating the human ratio behind such kinds of phenomena. Starting with an in-depth analysis of the phenomenon of Islamic radicalisation and its evolution throughout the years, this study is intended to delve into the core of online radicalisation to better understand the online dynamics involved in such processes and allow the reader to understand that online radicalisation is always connected with the offline world, an aspect that in the past was often underestimated in the understanding of such a phenomenon. The reader will then be accompanied through a journey that involves a multidisciplinary approach, with theories, data and information obtained through a mixture of communications studies, behavioural sociology, terrorism studies, international relations, history, and of course, European studies. As a conclusion of the first part of this study, the author provides a comprehensive overview of the existing different approaches for tackling online radicalisation, with a focus on the past and the actual European efforts being implemented in the fight against online radicalisation and terrorism that underlines its strengths and weaknesses. The second and third part of the thesis focus on a more practical approach to the issue, providing a critical opinion on how communication can be a special and efficient tool to understand and defeat online radicalisation and how this approach can be ameliorated and implemented by European actors to better tackle online radicalisation from a future standpoint. Relevance is given to counter-narratives as one of the most efficient ways of tackling the issue of online radicalisation, especially from a long-term perspective. The focus and attentive analysis is dedicated to counter-narratives and the reasons for their efficiency if implemented in a comprehensive way against the radical online propaganda of certain Islamist extremist groups. For this reason, the third part of the study guides the reader step by step through a proposed communications strategy for a European campaign against online radicalisation, with particular attention to all of the details of such a campaign, from its main message, to a well-defined target audience, from its method of implementation, partners, and funds, to how to evaluate its results. For this purpose, the study also includes an in-depth analysis on how big-data can help in building and evaluating such kinds of campaigns. As a conclusion to the study, the author, on both the communicative and political level, lists a set of “10 recommendations.” Finally, in support of the theories, examples, and recommendations illustrated by the author. Case studies and interviews are included as annexes of this study.