AbstractFluctuation patterns of physiological response after acute stress might indicate one's coping potential with stress, yet this relationship has not been widely examined. The present study investigated how Locus of Control (LOC) can influence cortisol and HR responses in an uncontrollable stressful situation. Seventy‐three participants were exposed to acute stress through the Trier Social Stress Test (TSST) after finishing the LOC measures. Multilevel regression results suggested that a curvilinear function best captured the shape of the cortisol trajectories which was further moderated by the level of internal LOC. Moreover, higher internality was associated with greater cortisol reactivity and faster recovery. Our study reveals the link between internal control and endocrine stress response. Finally, cortisol upregulation was discussed, as well as the internality‐related accelerated recovery of cortisol, which may be involved in the effect of motivation arousal for better adaptation.