The audience effect refers to the phenomenon that one？s performance on a task is affected by the presence of others. Here we investigated how the audience effect modulates the neurocognitive signatures underlying people？s evaluation of their own task performance/outcome. Participants in our study played a gambling game in two social contexts: an “audience” condition and an “alone” condition. The presence of others modulated the feedback-related negativity (FRN), which might reflect enhanced motivational significance or increased reward processing when participants were watched compared to when they were alone. We also observed increased P300 responses to outcome feedback in the audience condition, presumably reflecting more elaborative and sustained evaluation of outcomes in the audience than alone context. This audience effect on the evaluative processes complements previous observations on the social nature of outcome evaluation and extends a traditional topic in social psychology to the neuroscientific field.