<p>Social connection is essential to human health and survival. Experiences of ostracism increase vulnerability to psychopathology. Emotion regulation, supported by executive functions, may buffer these effects. However, prior research has mainly examined how ostracism impacts executive functioning, not the reverse. This study tested whether individual differences in inhibitory control, a key component of executive function, modulate neural and psychological responses to ostracism. Forty-two college students (age: 20.6 ± 2.0) completed multi-echo fMRI scanning, first performing a color-word Stroop task followed by the Cyberball task. Greater Stroop interference correlated with heightened activation in presupplementary motor area (pSMA) and dorsolateral prefrontal cortex (dlPFC). Using these signals as covariates in Cyberball analyses, we found that greater inhibitory inefficiency in pSMA coincided with reduced recruitment of the fronto-striatal regions implicated in emotion regulation and social monitoring, including dlPFC, dorsomedial PFC, and caudate nucleus, during ostracism. Notably, we modeled Cyberball by ball-tossing events, allowing us to see that within the Inclusion Block, individuals with inefficient inhibitory control in pSMA, elicited greater activation in these regions while watching others toss to each other vs. including the participant. This association was reversed in the Ostracism Block, where exclusion was explicit and sustained. This pattern suggests that inefficient inhibitory control may correlate with over-engagement of regulatory and social-monitoring systems in response to ambiguous cues of exclusion, followed by disengagement during actual ostracism. These neural patterns were associated with greater self-reported distress, suggesting that inhibitory inefficiency may increase vulnerability to the emotional consequences of social exclusion.</p>