Background: A better understanding of the correlates of nonsuicidal self-injury (NSSI) in children is important for the identification and prevention of future suicide risk. However, although abnormalities in reward responsiveness might constitute one potential transdiagnostic mechanism of risk for NSSI, no studies have examined initial response to reward in children with a history of NSSI. The goal of the present study was to address this important gap in the literature. To objectively assess initial response to reward, we utilized the feedback negativity (FN) event-related potential, a well-established psychophysiological marker of reward responsiveness. Methods: Participants were 57 children (19 with a history of NSSI and 38 demographically matched controls) between the ages of 7 and 11. Diagnostic interviews were used to assess for current and past DSM-IV mood and anxiety diagnoses and NSSI history. Children also completed a guessing task, during which continuous electroencephalography was recorded. Results: Children with a history of NSSI exhibited significantly more negative DFN (i.e., FN to losses minus FN to gains) than children without NSSI. These findings appeared to be at least partially independent of children’s history of psychopathology and current symptoms, suggesting their specificity to NSSI. Conclusions: These results provide initial evidence for heightened neural initial reward responsiveness to losses versus rewards in children with a history of NSSI. Pending replications and longitudinal studies, the DFN might represent a psychophysiological marker of risk for self-harm.