Objective Findings from prior research on reward sensitivity in nonsuicidal self-injury (NSSI) have been mixed. Childhood maltreatment is an independent risk factor for NSSI and for hyposensitivity to rewards. This study aimed to disentangle the role of reward sensitivity as a predictor of NSSI for those with an elevated severity of childhood maltreatment. Method In a diverse undergraduate sample (N = 586), trait reward sensitivity (i.e., behavioral approach system subscales) and the severity of maltreatment were assessed as predictors of a lifetime history of NSSI. In a subset of this sample (n = 51), predictors of NSSI urge intensity were measured using ecological momentary assessment. Results Individuals with elevated maltreatment who reported less positive responsiveness to rewards were more likely to have a lifetime history of NSSI. Those with elevated maltreatment who reported a lower likelihood to approach rewards experienced more intense NSSI urges across the ten-day observation period. However, those with elevated maltreatment who reported a greater likelihood to approach rewards experienced less intense NSSI urges. Conclusions The role of reward sensitivity as a cognitive risk factor for NSSI varies depending on childhood maltreatment history. Findings indicate that, for those with elevated maltreatment, hypersensitivity to approaching rewards may decrease risk for NSSI urges.