Introduction: Population aging is associated with a rising burden of non-communicable disease, profoundly impacting health policy and practice. Adopting and adhering to healthy lifestyles in middle or older age can protect against morbidity and mortality. Retirement brings opportunities to reconfigure habitual lifestyles and establish new routines. This study examines the longitudinal association between retirement and a range of lifestyle risk behaviors among a large population-based sample of Australian adults. Methods: Study sample included working adults aged ≥45 years at baseline (2006–2009, N=23,478–26,895). Lifestyle behaviors, including smoking, alcohol use, physical activity, diet, sedentary behavior, and sleep, were measured at both baseline and follow-up (2010). Logistic regression models estimated the odds of having each risk factor at follow-up and multiple linear regression models calculated the change in the total number of risk factors, adjusted for baseline risk and other covariates. Sociodemographic characteristics and reasons for retirement were tested as potential effect modifiers. Results: During the 3.3-year follow-up, about 11% of respondents retired. Retirement was associated significantly with reduced odds of smoking (AOR=0.74); physical inactivity (AOR=0.73); excessive sitting (AOR=0.34); and at-risk sleep patterns (AOR=0.82). There was no significant association between retirement and alcohol use or fruit and vegetable consumption. Change in the total number of lifestyle risk factors differed significantly by reason for retirement. Conclusions: In a large population-based Australian cohort, retirement was associated with positive lifestyle changes. Health professionals and policymakers should consider developing special programs for retirees to capitalize on the healthy transitions through retirement.