Objective: Intrusive memories are the hallmark feature of Post-Traumatic-Stress-Disorder (PTSD). Recent studies have found that a visuospatial intervention after viewing traumatic films reduces intrusive memories in healthy individuals. However, many individuals still exhibit high levels of symptoms following such an intervention, warranting continued investigation into specific characteristics moderating intervention effect. One such candidate is cognitive flexibility, defined as the ability to update behavior in accordance with contextual demands. The present study aimed at examining the interactive effect of cognitive flexibility and a visuospatial intervention on intrusive memories, predicting that higher flexibility would be linked to stronger intervention effects. Method: Sixty participants (Mage = 29.07, SD = 4.23) completed a performance-based paradigm evaluating cognitive flexibility, watched traumatic films, and were allocated to either an intervention or control group. Intrusions were assessed by means of laboratory and ambulatory assessment, and the Impact of Events Scale – Revised (IES-R). Results: Participants in the intervention group experienced fewer laboratory intrusions than the control group. However, this effect was moderated by cognitive flexibility: Whereas individuals with below-average cognitive flexibility did not benefit from the intervention, it was significantly beneficial for individuals with average and above-average cognitive flexibility. No group differences emerged in the number of ambulatory intrusions or IES-R scores. However, cognitive flexibility was negatively correlated with IES-R scores across both groups. Conclusions: These results highlight the significant role of cognitive flexibility in intrusion development, both in general and as a moderator of a visuospatial interventions. Future studies should investigate effects’ generalizability to clinical samples.