Climate change is a global issue affecting individuals, industries, and economies around the world. Many individuals know the risks of climate change and are willing to change their behaviour, but still contribute to high levels of greenhouse gas emissions. This discrepancy between willingness and action has been described as the attitude-behaviour gap. The current study used the theory of planned behaviour to explore the relationships between risk perception, behavioural willingness, constructive hope, and pro-environmental behaviour. An anonymous online questionnaire was completed by 300 participants (74.0% female) aged 18 years and over (M = 41.5 years). Self-report scales measured levels of risk perception, behavioural willingness, constructive hope, and pro-environmental behaviour. As predicted, risk perception was positively associated with behavioural willingness, risk perception and behavioural willingness were positively associated with pro-environmental behaviour, and constructive hope was positively associated with pro-environmental behaviour. Additionally, the positive relationship between behavioural willingness and pro-environmental behaviour was moderated by constructive hope. This finding may be particularly useful for environmental educators, policy makers, and communicators.