We examined the relation between aerobic fitness and inhibition in young children with and without attention deficit hyperactivity disorder (ADHD)-risk status. Participants (91 ADHD risk, 107 typically developing, Mage = 6.83, 53.5% male, 68.2% Caucasian) completed an assessment of aerobic fitness and a flanker task requiring variable amounts of inhibitory control. Aerobic fitness was positively associated with inhibition. When inhibitory control demands were largest, the relation varied as a function of ADHD-risk status such that the link between aerobic fitness and inhibition was significant only for children with ADHD risk. The relation between aerobic fitness, status, and inhibition was further moderated by age for interference control. Specifically, the positive relation between aerobic fitness and interference control was only significant for younger children with ADHD risk. A fitness-cognition link appears in young childhood that seems particularly salient for those in the earliest school years with ADHD risk. The findings extend work on typically developing children and suggest that exploring aerobic fitness interventions to address executive function impairments in children at risk for ADHD is warranted.