The association between lower resting heart rate and antisocial behavior has been suggested to be mediated by sensation-seeking. However, other theoretical models suggest that sensation-seeking has a moderating influence. This study sought to investigate the interplay between resting heart rate, sensation-seeking and antisocial behavior. Two subsets of participants from the Risk Factors for Antisocial Behavior (RFAB) project (n = 690, n = 391) were used. We conducted mediation analyses and logistic regression analyses to test for mediating and moderating effects of sensation-seeking on the association between resting heart rate and antisocial behavior by young adulthood. In general, sensation-seeking partially mediated the association between resting heart rate in childhood as well as adolescence and antisocial behavior by young adulthood. Resting heart rate in childhood and adolescence also interacted with sensation-seeking to predict antisocial behavior by young adulthood, such that a lower resting heart rate increased the odds of antisocial behavior among individuals with higher but not lower levels of sensation-seeking. Our results on a theoretical level suggest that sensation-seeking is important to understand the association between resting heart rate and antisocial behavior. Results further suggest that encouraging prosocial behaviors as a means of fulfilling the need for stimulation in individuals with a psychophysiological risk profile could serve as an effective approach in redirecting their behaviors towards positive outcomes.