BackgroundThe number of children in sexual minority parent families has increased. This systematic review aims to synthesise the evidence of disparities in family outcomes between sexual minority and heterosexual families and to identify specific social risk factors of poor family outcomes.MethodsWe systematically searched PubMed, the Web of Science, Embase, the Cochrane Library and APA PsycNet for original studies that compared family outcomes between sexual minority and heterosexual families. Two reviewers independently selected studies and assessed the risk of bias of included studies. Narrative synthesis and meta-analysis were conducted to synthesise evidence.ResultsThirty-four articles were included. The narrative synthesis results revealed several significant findings for children’s gender role behaviour and gender identity/sexual orientation outcomes. Overall, 16 of 34 studies were included in the meta-analyses. The quantitative synthesis results suggested that sexual minority families may perform better in children’s psychological adjustment and parent–child relationship than heterosexual families (standardised mean difference (SMD) −0.13, 95% CI −0.20 to −0.05; SMD 0.13, 95% CI 0.06 to 0.20), but not couple relationship satisfaction (SMD 0.26, 95% CI −0.13 to 0.64), parental mental health (SMD 0.00, 95% CI −0.16 to 0.16), parenting stress (SMD 0.01, 95% CI −0.20 to 0.22) or family functioning (SMD 0.18, 95% CI −0.11 to 0.46).ConclusionMost of the family outcomes are similar between sexual minority and heterosexual families, and sexual minority families have even better outcomes in some domains. Relevant social risk factors of poor family outcomes included stigma and discrimination, poor social support and marital status, etc. The next step is to integrate multiple aspects of support and multilevel interventions to reduce the adverse effects on family outcomes with a long-term goal of influencing policy and law making for better services to individuals, families, communities and schools.