Where low- and middle-income countries have limited economic resources to provide individualized mental health services to people exposed to conflict, community-based interventions may be more appropriate. We aimed to evaluate community level interventions for improving mental health outcomes in Low- and Middle-income countries (LMIC). A realist review of community-based interventions (CBIs) to improve mental health for people in LMIC following conflict. Five databases (Cochrane, PubMed, PsychINFO, Medline, and CINAHL) and a manual search of individual papers. We found 1318 articles, of which 29 were selected. Out of the 29 primary articles, 19 showed successful results, 4 showed mixed results, 1 showed inconclusive results, and 1 showed unsuccessful results. After analyzing the results, we found 3 mechanisms that may influence the effectiveness of these CBIs: the use of lay community members as intervention deliverers, the application of transdiagnostic approaches, and customized outcome assessment tools. Community-based approaches to improve mental health in LMICs are rare and evidence for their effectiveness is limited. Interventions that have a wide scope, train lay mental health workers, and use contextually adapted outcome assessment tools show promise.