Obesity is a public health problem. The global obesity problem has been attributed to unhealthy diet, inactivity, and hereditary factors. However, phthalates may also contribute to the obesity epidemic. The purpose of this cross-sectional study was to examine whether there was a relationship between exposure to phthalates and obesity among adults 18 years and older in the United States. The theoretical framework was based on the socioecological model. The quantitative, cross-sectional design, and data analysis were based on the National Health and Nutrition Examination Survey, 2011-2012 database. Descriptive statistics and multiple regression analysis were used to analyze the association between phthalates, obesity, and other independent variables (phthalates exposure, socioeconomic status, gender, age, race/ethnicity, physical activity and place of residence) According to study results, exposure to phthalates does not have a statistically significant effect on the odds of obesity. In terms of the influence of the sociodemographic variables such as race, age, and gender on the relationship between total phthalate exposure and obesity, only race showed statistical significance at p < 0.05. In addition, physical activity did not have influence on relationship between total phthalate exposure and obesity among adults 18 years and older in the United States. Despite the lack of significant relationships, the results of this study are useful in addressing the concerns about the exacerbation of obesity. The results of this study could enhance academic research by showing the effect of phthalate chemical exposure, age, gender, race/ethnicity, physical activity, income, and educational level on obesity.