Attention-deficit/hyperactivity disorder (ADHD) and eating disorders are common and concerning mental health disorders. There is both empirical and theoretical support for an association between ADHD and eating disorders or disordered eating. This systematic review aims to summarize the extant literature on the comorbidity of ADHD and eating disorders across the lifespan, including the influences of sex, age, eating disorder diagnosis, and potential mediators. A total of 37 peer-reviewed studies on diagnosed ADHD and eating disturbances were identified through key research databases. Twenty-six studies supported a strong empirical association between ADHD and eating disorders or disordered eating. The systematic review findings suggest that children with ADHD are at risk for disordered eating, while adolescents, emerging adults, and adults are at risk for both eating disorders and disordered eating. Methodological considerations, future research, and clinical implications are discussed.