BackgroundTrans and gender-diverse individuals experience disproportionate rates of discrimination and poor mental health. Discrimination often occurs as microaggressions (i.e. intentional or unintentional behaviors and statements that communicate hostile or derogatory messages toward members of marginalized groups). Microaggressions adversely impact the mental health of marginalized groups. However, little is known about their impact on the mental health of trans and gender-diverse people. We aimed to summarize existing research on the impact of microaggressions on the mental health of trans and gender-diverse people and provide insight into limitations, directions for future research, and clinical implications.MethodsWe employed a scoping review methodology following JBI and Preferred Reporting Items for Systematic Reviews and Meta-Analyses scoping review guidelines. We searched five databases (PubMed, PsychINFO, CINAHL, Web of Science and Embase) from database inception to May 2024.ResultsOur review yielded seven quantitative, two qualitative, and three mixed methods studies. While findings were mixed, most included studies found that microaggressions toward trans and gender-diverse people were associated with adverse mental health outcomes, including increased emotional exhaustion, stress, anxiety, depression, and suicidal ideation and attempts, and decreased quality of life.ConclusionOur findings suggest that clinicians caring for trans and gender-diverse people would benefit from education about microaggressions and their impacts and guidance about how to create an affirming environment. Several included studies used measures of microaggressions that are less applicable to trans and gender-diverse people, and as such, it is recommended that future research utilizes measures developed and validated for trans and gender-diverse populations.