This study aimed to examine whether the metacognitive system monitors the potential positive effects of gestures on spatial thinking. Participants (N = 59, 31F, Mage = 21.67) performed a mental rotation task, consisting of twenty-four problems varying in difficulty, and evaluated their confidence in their answers to problems in either gesture or control conditions. The results revealed that performance and confidence were higher in the gesture condition, in which the participants were asked to use their gestures during problem-solving, compared to the control condition, extending the literature by evidencing gestures` role in metacognition. Yet, the effect was only evident for women, who already performed worse than men, and when the problems were difficult. Encouraging gestures adversely affected performance and confidence in men. Such results suggest that gestures selectively influence cognition and metacognition and highlight the importance of task- (i.e., difficulty) and individual-related variables (i.e., sex) in elucidating the links between gestures, confidence, and spatial thinking.