Although micro- and nanoplastics (MNPs) represent one of the main environmental emergencies worldwide, citizens are not always aware of their active role in contributing to such contamination. In this study, the perception, level of knowledge, and behaviours towards MNPs were assessed in young citizens in Modena (Italy), represented by science-oriented Bachelor’s students (n = 220) enrolled at the university, through the administration of a voluntary-based questionnaire. No differences in knowledge and in students’ attitudes were observed according to gender and the undergraduate program. Students seem to be aware of MNPs’ global distribution and effects on ecosystems but were less advised about MNP types and their potential effects on human health. A positive correlation between the students’ level of concern and their knowledge or their behaviour was found. Differently, no correlation between students’ knowledge and behaviour towards plastic and MNP contamination was observed. Thus, having a good knowledge of the issue does not always translate into effective actions planned to mitigate the problem. As a first step forward, more environmental education programs should be promoted to increase knowledge and awareness in young citizen as well as pro-environmental behaviours to pursue future mitigation strategies.