Over the past decade, evidence has accumulated to suggest that bisexual people experience higher rates of poor mental health outcomes compared to both heterosexual and gay/lesbian individuals. However, no previous meta-analyses have been conducted to establish the magnitude of these disparities. To address this research gap, we conducted a systematic review and meta-analysis of studies that reported bisexual-specific data on standardized measures of depression or anxiety. Of the 1,074 full-text articles reviewed, 1,023 were ineligible, predominantly because they did not report separate data for bisexual people (n = 562 studies). Ultimately, 52 eligible studies could be pooled in the analysis. Results indicate that across both outcomes, there is a consistent pattern of lowest rates of depression and anxiety among heterosexual people, while bisexual people exhibit higher or equivalent rates in comparison to lesbian/gay people. On the basis of empirical and theoretical literature, we propose three interrelated contributors to these disparities: experiences of sexual orientation-based discrimination, bisexual invisibility/erasure, and lack of bisexual-affirmative support. Implications for interventions to improve the health and well-being of bisexual people are proposed.