The aim of this study was to examine the mediating role of theory of mind (ToM) skills in the relationship between cognitive flexibility and mindfulness in middle childhood. The study group comprised 282 children aged 9 to 11 years who were attending two separate primary schools in Ankara, Türkiye. The children were administered a battery of instruments consisting of self-report measures of cognitive flexibility and mindfulness in addition to a story-based assessment of ToM. To test the hypotheses of the study, a serial multiple mediation model was employed. The findings of the study indicated that cognitive flexibility had a positive and significant impact on mindfulness. Although the specific single mediating impact of the first-order false belief task (ToM1) on the relationship between cognitive flexibility and mindfulness was not significant, the impacts of the second-order false belief task (ToM2) and the faux pas task (ToM3) were found to be significant. Furthermore, the findings indicated that the ToM1, ToM2, and ToM3 skills collectively exerted a serial multiple mediating impact on the relationship between cognitive flexibility and mindfulness. The results are significant in elucidating the cognitive and emotional developmental processes in the middle childhood context, and they underscore the importance of strategies to improve children's cognitive flexibility and ToM skills in educational and psychological interventions.