Emerging adulthood is a transitional life stage with increased probability of risky and unhealthy lifestyle behaviours that are known to have strong links with premature mortality and morbidity. Wellbeing, as a positive subjective experience, is identified as a factor that encourages self-care and may steer individuals away from risky lifestyle behaviours. Investigating wellbeing–behaviour links in the emerging adult population may increase understanding of the factors that lead to, and ways to prevent, engagement in risky behaviours. This study examines the association between flourishing, that is, the experience of both high hedonic and eudaimonic wellbeing, and a broad range of risky and unhealthy lifestyle behaviours among emerging adults in Australia. A cross-sectional survey of 1155 emerging adults aged 18–25 years measured wellbeing, socio-demographics, and six groups of lifestyle behaviours surrounding substance use, physical activity, diet, sex, sun protection, and driving. Bivariate and multivariate statistics were used to analyse the data. The findings revealed that flourishing was negatively associated with more dangerous types of risk behaviours, such as driving under the influence of drugs, and positively associated with self-care behaviours, such as healthier dietary behaviour and sun protection. If enabling emerging adults to flourish can contribute to reduced engagement in risky/unhealthy lifestyle behaviours, then promoting it is an important goal for health promotion efforts not only because flourishing is desirable in its own right, but also to bring about sustainable change in behaviour. Further research is needed to inform the designs of such interventions.