<p>Civic engagement, including activities like volunteering, is generally associated with positive developmental outcomes in youth (e.g., sense of belonging), but its associations with mental health remains uncertain. This systematic review explored longitudinal associations between youth civic engagement and mental health. A systematic search of MEDLINE, PsycINFO, and EMBASE was conducted for studies up to November 14, 2024. This review included English peer-reviewed longitudinal studies involving youth aged 15–30 that examined civic engagement and mental health. Risk of bias was assessed with the Newcastle–Ottawa Quality Assessment tool. Thirteen articles were included for this review. Volunteering was the most studied civic activity (<i>n</i> = 5), with depressive symptoms (<i>n</i> = 12) as the primary mental health outcome. Narrative synthesis suggests mixed findings: volunteering was typically associated to positive mental health outcomes, while political behaviors and voting, showed mixed or null associations. Youth with better mental health were more likely to engage in civic activities, though some studies found no significant association. These findings highlight the complex association between civic engagement and mental health, underscoring the need for further exploration of this bidirectional relationship and the importance of creating resources and supportive environments to help youth navigate and cope with negative civic experiences.</p>