Increased access to digital technologies and social media has created new opportunities and challenges for education. Digital tools are used by schools to support teaching, learning and interaction, enhance professional development and more recently to facilitate emergency remote education. These digital practices, however, also challenge existing pedagogical models and raise questions in relation to teachers’ critical digital literacies. Furthermore, teachers play a key role in ensuring that the younger generations acquire knowledge and skills relevant for taking a critical disposition towards various phenomena and practices in the digitalised world. Against this context, this paper presents the findings of a qualitative study that intended to develop an understanding of teachers’ perceptions, experiences and needs in relation to critical digital literacies. The empirical findings were used to inform and finalise the design of a new Critical Digital Literacy (CDL) framework for primary and secondary teachers and schools across Europe. According to the interview analysis, the CDL framework captured all relevant aspects of critical digital literacies in the school context. While different sub-dimensions of CDL were reported to be more prevalent for each national group, the framework facilitated focusing on specific transversal issues which require attention across European schools. Additionally, the findings are particularly relevant in light of the Covid-19 related school closures and the move to online learning since the teachers acknowledged in the interviews how enhancing their own and their students’ critical digital literacies appeared to be more important than ever before.