Despite increasing research on the mechanisms that underlie the relation between perceived overqualification (POQ) and extra-role behaviors, the relation's affective mechanisms have been understudied. In this study, we focus on the role of job boredom among overqualified workers in order to understand two types of extra-role behaviors: counterproductive work behaviors (CWB) and organizational citizenship behaviors (OCB). Using a sample of white-collar employees in South Korea (N = 298), we found that job boredom fully mediated the effects of POQ on CWB and OCB after controlling for the effects of state anger and neuroticism. We additionally examined whether career calling moderates the indirect effects of POQ on CWB and OCB via job boredom and found career calling mitigated the negative indirect effect of POQ on OCB via job boredom. However, career calling did not moderate the positive indirect effect of POQ on CWB. Implications of these findings are discussed.