Objective Because melanoma patients are at high risk of further disease, we aimed to study their melanoma prevention behaviours. Methods In a large cohort of patients newly diagnosed with high‐risk melanoma in Queensland, Australia, we assessed clustering of preventive behaviours using latent class analysis. We assessed associated factors with prevalence proportion ratios (PPRs) and 95% confidence intervals (CIs) estimated by Poisson regression, and also if preventive behaviour was associated with better tumour prognosis at diagnosis. Results Among 789 primary melanoma patients (57% male; 21% with previous melanoma), we identified 4 different behaviour clusters: “no/ low prevention” (34% of cohort), “sun protection only” (25%), “skin checks only” (25%) and “sun protection and skin checks” (16%). Prevalence of clusters differed between males and females and also the component behaviours. Preventive behaviours were associated with having skin that burned and past cutaneous cancer, and for males, combined sun protective and skin checking behaviour was associated with higher education and non‐smoking. In patients with no past history of cutaneous cancer, males in the “skin checks only” cluster had significantly reduced chances of a thick (poor prognosis) melanoma (PPR = 0.79, 95% CI 0.68, 0.91) and females in the “sun protection and skin checks” cluster were significantly less likely to have an ulcerated melanoma (PPR = 0.85, 95% CI 0.74, 0.98) compared with the “no/ low prevention” cluster. Conclusion These findings allow tailoring of preventive advice to melanoma patients to reduce their risk of future primary and recurrent disease.