The widespread adoption of smartphones has been associated with the emergence of problematic smartphone use. Problematic smartphone use is consistently associated with increased levels of depression and lower self-control, and pathological technology use more generally may be associated with reduced activity in the reward system, an effect that is also observed in depression and with poor self-control. The current study sought to examine the association between problematic smartphone use and event-related potentials (ERPs) related to reward processing, and to determine whether reward processing, depressive symptoms and self-control have shared or unique influences on problematic smartphone use. The sample was drawn from a university student population (N = 94, age M = 19.34, SD = 1.23 years, 67 female, 25 male, 1 gender non-conforming, 1 unidentified). Participants performed a gambling task while EEG was recorded and completed measures of smartphone pathology, depressive symptoms and self-control. The ERP data revealed that increasing problematic smartphone use was associated with reduced ERP amplitude for gains and losses when individuals were the agent of choice, but not when the computer chose. This may reflect a selective association between problematic smartphone use and neural prediction errors. Regression analyses revealed that reward processing, depressive symptoms and self-control were predictors of problematic smartphone use, possibly revealing multiple pathways to problematic smartphone use.