Studies of the general population suggest that the risk for mental health difficulties conferred by dispositional behavioural inhibition (BI) may be modified by self-regulation; however, this possibility has not been explored in the context of autism. This study investigated the moderating effects of attentional-, activation-, and inhibitory control on the relationship between childhood BI and anxiety and depression among 47 autistic youths (55% male, M[subscript age] = 19.09 years, SD = 2.23). Childhood BI was associated with anxiety at low but not high levels of attentional- and activation control, and depression at low but not high levels of attentional control. However, there were no moderating effects of inhibitory control. These preliminary findings are partially consistent with those from the general population and point to avenues for future work.