Purpose: This study aims to investigate the impact of disadvantaged neighborhoods and lifestyle factors on obesity among Australian adults. Design: Quantitative, longitudinal research design. Setting: Cohort. Sample: Data for this study came from a cohort of 10 734 adults (21 468 observations) who participated in the Household, Income and Labour Dynamics in Australia survey. The participants were interviewed at baseline in 2013 and were followed up in 2017. Measures: Generalized Estimating Equation model with logistic link function was employed to examine within-person changes in obesity due to disadvantaged neighborhoods and lifestyle factors at 2-time points over a 4-year follow-up period. Results: Adults living in the most disadvantaged area were 1.22 (odds ratio [OR]: 1.22, 95% CI: 1.08-1.38) and 1.30 (OR: 1.30, 95% CI: 1.20-1.42) times, respectively, more prone to be overweight and obese compared with peers living at least disadvantaged area. Study results also revealed that adults who consume fruits regularly and perform high levels of physical activity were 6% (OR: 0.94, 95% CI: 0.91-0.98) and 12% (OR: 0.88, 95% CI: 0.85-0.92) less likely to be obese, respectively, compared to their counterparts. Current alcohol drinkers were 1.07 (OR: 1.07, 95% CI: 1.01-1.13) times more likely to be obese compared to peers not consuming alcohol. Highly psychologically distressed adults were 1.08 times (OR: 1.08, 95% CI: 1.02-1.13) more likely to be obese than their peers. Conclusion: This study contributes to the literature regarding disadvantaged neighborhoods and lifestyle factors, which have an influence on adult obesity rates and thus help health decision-makers to formulate effective obesity prevention strategies.