Abstract Background Disease-free survival (DFS) and overall survival (OS) associations with anthropometric measures of obesity and changes in these exposures remain unknown among endometrial cancer survivors. Methods Endometrial cancer survivors diagnosed between 2002 and 2006 completed direct anthropometric measurements and self-reported lifetime weight history during in-person interviews approximately 4 months after diagnosis (peridiagnosis) and approximately 3 years after diagnosis (follow-up). Participants were followed-up until death or March 20, 2019. Cox proportional regression was used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for body mass index (BMI), weight, waist circumference, and waist-hip ratio with DFS and OS. Statistical tests were 2-sided. Results A total of 540 and 425 cancer survivors were assessed peridiagnosis and follow-up, respectively. During the median 14.2 years of follow-up (range = 0.3-16.5 years), 132 participants had a recurrence and/or died (DFS), with 111 deaths overall (OS). Reduced DFS was noted with greater recalled weight 1 year before diagnosis (HR = 1.88, 95% CI = 1.15 to 3.07), BMI 1 year before diagnosis (HR = 1.88, 95% CI = 1.09 to 3.22), and measured peridiagnosis BMI (HR = 2.04, 95% CI = 1.18 to 3.53). Measured peridiagnosis waist circumference of at least 88 cm was associated with decreased DFS (HR = 1.94, 95% CI = 1.24 to 3.03) and OS (HR = 1.90, 95% CI = 1.16 to 3.13). A twofold decrease in DFS and OS was associated with a BMI of at least 5% or weight change from 1 year before diagnosis to peridiagnosis. No associations were observed for the assessment during follow-up. Conclusions One-year before- and peridiagnosis anthropometric measures of obesity were associated with reduced survival among endometrial cancer survivors. Anthropometric changes from 1 year before to peridiagnosis may provide an important indication of future survival in this population.