The objective of this study is to determine the prevalence and correlates of obesity among youth investigated for maltreatment in the United States. Participants were drawn from the National Survey of Child and Adolescent Well-Being II, a national probability study of 5,873 children aged birth to 17 years under investigation for maltreatment in 2008. From child weight reported by caregivers, we estimated obesity (weight-for-age ≥95th percentile) prevalence among children aged 2 through 17 (n=2,948). Sex-specific logistic regression models by developmental age were used to identify obesity risk factors, including child age, race/ethnicity, and maltreatment type. Obesity prevalence was 25.4% and was higher among boys than girls (30.0% vs. 20.8%). African American adolescent boys had a lower risk for obesity than white boys (OR=0.28, 95% CI [0.08, 0.94]). Compared with girls aged 2–5 with a neglect allegation, girls with a sexual abuse allegation were at greater risk for obesity (OR=3.54, 95% CI [1.01, 12.41]). Compared with adolescent boys with a neglect allegation, boys with a physical abuse allegation had a lower risk for obesity (OR=0.24, 95% CI [0.06, 0.99]). Adolescent girls with a prior family history of investigation were at greater risk for obesity than those without a history of investigation (OR=3.97, 95% CI [1.58, 10.02]). Youth investigated for maltreatment have high obesity rates compared with national peers. Opportunities to modify and evaluate related child welfare policies and health care practices should be pursued.