This study aimed to provide data on the impact of known risk factors on endometrial cancer burden. Using data on 1199 endometrial cancer cases and 1212 frequency matched controls from a population-based case–control study carried out in urban Shanghai, China from 1997 to 2003, multivariable adjusted odds ratios were obtained from unconditional logistic regression analyses. Partial population-attributable risks were calculated and corresponding 95% confidence intervals were estimated using a bootstrap method. An estimated 16.94% of endometrial cancer cases were attributed to overweight or obesity; 8.39% to meat intake; 5.45% to nonregular tea drinking; 5.23% to physical inactivity; and 1.77% to family history of endometrial, breast, or colorectal cancers. Overall, these risk factors accounted for 36.01% (95% confidence interval: 28.55–43.11%) of total endometrial cancer cases. Similar results were observed when analysis was restricted to postmenopausal women. Among modifiable lifestyle factors, overweight and obesity accounted for the largest proportion of endometrial cancer in the study population. Lifestyle alterations, such as maintenance of healthy weight, regular exercise, consumption of less meat, and tea drinking, could potentially reduce endometrial cancer by more than one-third.