A major control demand in successful dual-task performance is the task-specific separation of task-goal representations and of the related stimulus-response translation processes. In the present study, we investigated how these cognitive control processes of task shielding are affected by acute psychosocial stress. Fifty-six healthy participants were exposed to either an acute psychosocial stressor (the Trier Social Stress Test) or a standardized control situation prior to a dual task. Task shielding was assessed by analyzing the interference of Task 2 processing on prioritized Task 1 performance. Following successful stress induction, as indicated by increases in salivary α-amylase (sAA) and cortisol that reflect increases in sympathetic nervous system and hypothalamus-pituitary-adrenal (HPA) axis activity, respectively, stressed individuals displayed reduced task shielding relative to controls. This result was further substantiated by a correlation between treatment-related increase in cortisol, but not sAA, and between-task interference, suggesting a potential role of the HPA stress response for the development of the observed effects. As an additional finding, when the volunteers were categorized with regard to their action-state orientation, their orientation did not interact with stress but did reveal generally increased between-task interference, and thus inferior task shielding, for state-oriented as compared to action-oriented individuals.