This study investigates how Foucauldian ideas affect undergraduates at Olabisi Onabanjo University in Nigeria to adopt sustainable practices for reducing plastic waste. It aims to comprehend how Foucault's historical ontology of subjects, subjectivation, and self-practices might inspire tactics for promoting sustainable behaviours, particularly in the reduction of plastic waste. The study attempts to do this by investigating how subjectivation changes individual attitudes and behaviours towards minimising plastic waste, as well as how discourses and power dynamics influence self-practices that lead to sustainable behaviours. The study also intends to evaluate the efficacy of interventions that target subjectivation and self-practices in encouraging sustainable behaviours in plastic trash reduction. The theoretical foundation of the study is based on Foucauldian theory, social practice theory, behavioural change theories, environmental psychology, and systems theory. To achieve these goals, a descriptive study approach was used, with qualitative data collecting and content analysis. Undergraduate students from Olabisi Onabanjo University in Nigeria participated in the qualitative data gathering. Their findings offer important views on sustainable behaviours and approaches for reducing plastic waste. The findings of this study have the potential to inform the development of more effective interventions and methods for combating plastic waste pollution, adding to global environmental sustainability initiatives.