Gestures support communication and mental processes. However, the contribution of co-speech gestures to autobiographical retrieval has recently started to receive attention. This study examines whether gestures facilitate autobiographical constructions by activating existing episodic details and integrating new ones, through a within-participant manipulation of gesture use (spontaneous and encouraged) and event type (past and future). Our main findings showed that representational gestures accounted for an increase in episodic details within autobiographical memory constructions. Although participants gestured more when they were encouraged, and past events elicited more details than future events, the association between gestures and increased episodic details did not differ across conditions. These findings suggest that representational gestures are particularly instrumental in autobiographical memory processes, as they contribute to the activation and retrieval of episodic details in mental simulations.