In the twenty-first century, while the internet has transformed global communication and personal interactions, it has also become a tool for criminal groups such as terrorists to exploit vulnerable children. The chapter aims to examine the complex relationship between the internet and the radicalisation of children by terrorist and extremist groups. To this end, the chapter explores how contemporary digital technologies contribute to the recruitment and manipulation of minors by extremist organisations. Furthermore, the chapter covers the impact of the internet on facilitating terrorism through various online channels, the specific methods used by terrorists to target and radicalise children, and the advantages of using minors in terrorist operations. Additionally, it highlights the distinct exploitation of female children and reviews strategies for countering online radicalisation including rehabilitation and parental oversight. By addressing these issues, the chapter seeks to provide a comprehensive understanding of the factors driving children’s involvement in extremism and to propose effective interventions to prevent their exploitation.