The 2030 Agenda sets out seventeen Sustainable Development Goals (SDGs). The educational goal is to promote the education of citizens on sustainable development, among other things. Educating today's digital citizens on sustainability means training them for justice and social activism, commitment and political engagement. However, research into the subject shows a lack of consistency in the education of university students. This paper presents a study of students of Education, on education on sustainability through the practice of active and critical digital citizenship. A quasi-experimental method was used to learn about the behaviours of digital citizens, and intervention was carried out by means of an SDG-focused workshop and observation of the final level of commitment. The results show a positive level of commitment and digital activism around content related to sustainable development, which can be addressed from the university syllabus in a cross-curricular way.