Background: Impulsivity is a core feature of attention-deficit/hyperactivity disorder (ADHD). Previous work using the delay discounting task to assess impulsivity reveals that adolescents with ADHD tend to prefer a smaller-immediate reward over a larger-delayed reward, and this relates to problematic choices in daily life. To gain a better understanding of daily decision-making in adolescence, it is important to examine the social context, as peers have a major influence on decisions. Peer influence often has a negative connotation, but also provides an opportunity to promote positive outcomes. To date, it is unclear if peers affect impulsive decision-making in adolescents with ADHD, for better or for worse. Methods: The aim of this preregistered study was to examine the effect of peer feedback on impulsive choice in male adolescents with and without ADHD (ages 13-23; N = 113). We utilized an adapted delay discounting task that was administered alone, in a social condition, and alone again. In the social condition, adolescents received either (between-subjects) manipulated impulsive or non-impulsive peer feedback. Impulsive peer feedback consisted of likes for choosing the smaller immediate reward, whereas non-impulsive peers endorsed choosing the larger delayed reward. Results: Preregistered analyses showed that non-impulsive peer feedback resulted in decreased impulsive choice, whereas impulsive peer feedback did not alter decision-making in adolescents with and without ADHD. Explorative analyses of inattention and hyperactivity-impulsivity symptoms in the total sample, irrespective of diagnosis, showed that lower hyperactivity-impulsivity and more inattention symptoms were associated with increased susceptibility to non-impulsive peer feedback. Conclusions: Together, these findings indicate that peers may provide an opportunity to decrease impulsivity and emphasize individual differences in susceptibility to non-impulsive peer feedback related to inattention and hyperactivity-impulsivity. Therefore, peer feedback may be a promising component in behavioral peer-supported interventions in adolescents with ADHD.