Background <p>Prior studies have examined the impact of armed conflict on mental health. This systematic review synthesizes evidence on how peace and conflict resolution interventions influence the mental health and well-being of conflict-affected communities.</p> Methods <p>We conducted a systematic review across multiple databases and identified studies evaluating the effects of peace and conflict resolution interventions on mental health and well-being from 1990 to 2026. Due to heterogeneity in study designs and outcomes, a narrative synthesis was conducted.</p> Results <p>The search yielded 6,360 records, of which 15 were included. The majority of studies were cross-sectional (<i>n</i> = 6), and only two were randomised controlled trials (RCTs). Most studies were conducted in African countries, targeted the community level, and were implemented by government agencies or non-governmental organisations (NGOs). Overall, studies yield mixed mental health outcomes. On the one hand, rehabilitation programmes, reparations support, financial aid, and reconciliation media show positive effects on psychological well-being. However, truth and reconciliation interventions were associated with negative outcomes, as they exacerbate distress, posttraumatic stress disorder, and anxiety, particularly for survivors. Most studies were limited by a focus on short-term effects and lack of a comparison group.</p> Conclusion <p>The findings present a mixed picture: while rehabilitation and economic interventions show mental health benefits, truth and reconciliation efforts were associated with psychological harms. More longitudinal studies with larger samples and rigorous designs are needed to assess long-term effects. Recognising both the mental health risks and benefits of peace and conflict interventions is essential to ensure they support not only political stability but also psychological recovery and resilience.</p>