This study aimed to explore the relationships between situational and psychological factors and Hong Kong citizens' plastic waste management (PWM) intentions based on an extended theory of planned behaviour model with situational factors. A total of 996 Hong Kong permanent residents were surveyed, and data were analysed using structural equation modelling. The results revealed that situational factors had a direct and positive effect on PWM intention, but also affected PWM intention indirectly through their significant effects on attitude and perceived behavioural control regarding PWM. The implications for environmental education and policy are discussed.