Background: Poor and insufficient social support to the mother in the post-partum period impairs the effective functioning of her new role as a mother, and it is an important risk factor for the maternal depression and stress after childbirth. Thus, interventions to improve social support to mothers in their postpartum period are required. The present review aimed to investigate the effectiveness of the existing interventions aimed at improving social support among postpartum women. Methods: In this systematic review, PubMed, Scopus, Science Direct, Cochrane Library, Web of Science, EMBASE, Google Scholar, IranDoc, IranMedex, MagIran and SID were searched until January 2022. Full-text articles on the social support outcome, published in English or Persian, which used the design of randomized controlled trials (RCTs) or comparison groups and involved postpartum or pregnant women as participants were included. The quality of the studies was assessed based on the seven criteria offered by Cochrane guidelines. Results: Our review included 10 studies involving 3328 women. According to our results, the following interventions were successful in increasing social support compared to the controlled conditions: counseling with men in the prenatal period, interventions based on interpersonal psychotherapy (IPT), advanced practice nurse (APN), internet support, and home visiting in the postpartum period. Conclusion: These interventions could be provided to mothers during their prenatal or postpartum care. However, which one of these interventions is the most effective in improving social support among postpartum mothers was not identified in the present study.