While the influence of state-dependent factors on appetitive processing has received considerable attention, the role of stable personality traits remains comparatively unexplored. Extraversion, characterized by heightened positive emotionality, represents a compelling candidate in this regard, as it may shape individual differences in Positive Valence System (PVS) functioning. The present study examined how extraversion modulates neural and subjective responses to pleasant stimuli; the role of neuroticism was additionally explored, given its established association with affective reactivity. Sixty-eight Italian university students (40 females) completed an online version of the Big Five Inventory (BFI-44) before the laboratory session. Then, participants completed a passive viewing task of pleasant and neutral images while undergoing an electroencephalographic (EEG) recording. Appetitive stimulus processing was indexed by the peak amplitude of the P300-LPP complex and subjective SAM ratings. Results revealed that extraversion was positively associated with larger P300-LPP complex amplitudes to pleasant relative to neutral stimuli and with higher arousal ratings across both emotional categories. Additionally, neuroticism was associated with lower valence ratings regardless of stimulus category, with no significant effect on neural responses to emotional stimuli. These findings highlight extraversion as a stable personality trait shaping PVS functioning. Specifically, low extraversion was associated with reduced P300–LPP amplitudes and lower arousal ratings to pleasant stimuli, paralleling neural patterns documented in psychopathological conditions involving blunted PVS activation. These results underscore the utility of ERP-based measures in capturing personality-related differences in appetitive processing relevant to psychopathology risk.