Children with attention-deficit/hyperactivity disorder (ADHD) often show executive function (EF) problems and neurophysiological hypoarousal. Baroreceptor activation, as part of the baroreflex short-term blood pressure regulatory mechanism, has been linked to cortical inhibition and attenuated cognitive-attentional functioning. We investigated the hypothesis that higher resting baroreflex sensitivity (BRS) predicts poorer EF performance in children with ADHD. EF measures of speed and accuracy were regressed upon resting BRS in 10-12-year-old children with ADHD from a clinic-referred sample (n=181) and healthy (n=194) and clinic-referred (n=260) comparison samples. Resting BRS was positively associated with poorer EF performance (e.g., response variability, working memory, response inhibition), especially in ADHD combined type, boys, and unmedicated children. Comparison samples partly suggested negative associations. We conclude that higher resting BRS is related to poorer cognitive performance in children with ADHD. Findings suggest afferent influences of the body's visceral state on higher-order cognitive functioning and imply energetic state dysregulation in ADHD.