Social rejection elicits distress through the brain's alarm system, the dorsal anterior cingulate cortex (dACC). The distress of rejection facilitates subsequent inclusion. As a result, traits that blunt this dACC response to social rejection might then threaten group membership, leading to further subsequent rejection. Alexithymia, the inability to identify and describe affective states, is associated with social impairment and reduced dACC activity under conditions of negative affect. Thus, we expected that alexithymia would relate to less dACC activation during rejection and that this blunted response would explain an association between alexithymia and greater rejection in everyday life. Using functional magnetic resonance imaging and daily diaries, we found that subclinical individual differences in the core feature of alexithymia, difficulty identifying affect, was associated with a blunted dACC response to social rejection. Deficits in affect identification were also associated with greater daily rejection and that this effect was mediated and suppressed by dACC activation to rejection. Our findings emphasize the crucial role of the dACC in response to social rejection and extend the literature on alexithymia's ability to dampen neural responses and contribute to poor social functioning. The suppressing role of the dACC suggests future directions for clinical interventions on those with affective disorders.