Aim <p>With the incidence of preventable chronic diseases on the rise, it is vital to understand factors that support ageing well. Trait mindfulness is a positive psychological resource that may offer potential as a health asset. This study aimed to understand whether community-level evidence supports this claim.</p> Subject and methods <p>In this cross-sectional study, data were collected from older Australians (<i>n</i> = 838) via self-report in online surveys (mean 65&#xa0;years). Hypotheses were tested using regression models. We tested the relationship of trait mindfulness with health risk behaviours, disease diagnoses, mental health and health-related quality of life (HR-QoL) then investigated its potential for moderating the effects of health decline on HR-QoL.</p> Results <p>Trait mindfulness was negatively associated with the reported number of diseases, the number of health risk behaviours and depression symptoms; and was positively associated with HR-QoL (all <i>p</i> &lt; .001). Further, trait mindfulness moderated the negative influence of multiple disease diagnoses (<i>p</i> = .015), but not depression, on HR-QoL.</p> Conclusion <p>Cross-sectional data show trait mindfulness is associated with lower rates of chronic disease, better attendance to health risk factors and buffers the negative effect of multimorbidity on HR-QoL. The finding that trait mindfulness did not moderate the effects of depression on HR-QoL requires further research. Understanding if these effects can be explained by stress-buffering or empowerment pathways, or both is worth pursuing, to inform public health intervention.</p>