Flexible use of emotion regulation (ER) strategies is central to mental health. To advance our understanding of what drives adaptive strategy‐switching decisions, in this preregistered study, we used event‐related potentials (late positive potential, LPP and stimulus preceding negativity, SPN) and facial electromyography (EMG corrugator activity) to test the antecedents and consequences of switching to an alternative ER strategy. Participants (N = 63, Mage = 24.8 years, all female) passively watched and then implemented an instructed ER strategy (reappraisal or distraction) in response to high‐intensity negative pictures that were either easy or difficult to reinterpret (high or low reappraisal affordance, respectively). Next, they decided to “switch from” or “maintain” the instructed strategy and subsequently implemented the chosen strategy. Reappraisal affordance manipulations successfully induced switching. Regarding antecedents, switching was predicted by the reduced ER efficacy of the current strategy (corrugator, but not LPP). Switching to distraction was additionally predicted by increased responses to the stimulus during passive viewing (corrugator and LPP) and increased anticipatory effort in implementing reappraisal (SPN). Concerning consequences, switching to distraction improved, whereas switching to reappraisal impaired post‐choice ER effects (LPP). However, starting with reappraisal was overall more effective than starting with distraction, irrespective of the subsequent decision (corrugator). Our results suggest that switching between ER strategies occurs in accordance with situational demands (stimulus affordances) and is predicted by reduced peripheral physiological ER efficacy. However, only switching to distraction leads to improved regulatory effects. These insights provide neurocognitively grounded starting points for developing interventions targeting ER flexibility.