BackgroundFew studies have examined the inter-relationships between teacher and student mental health. We aimed to examine associations between teacher distress and student mental health difficulties and if student perceptions of school safety moderate these associations.MethodData from 23,568 students in grades 6–12 and 1,478 teachers from 268 schools participating in the School Mental Health Surveys in Ontario, Canada, were used. Three-level (student, classroom, school) multivariable linear regression models were fit to examine associations between teacher distress and student internalizing and externalizing symptoms by elementary (grades 6–8) and secondary (grades 9–12) school. Statistical interactions were used to evaluate effect modification.ResultsSmall but statistically significant, positive associations were found between teacher distress and internalizing (b = 0.02; 95% CI [0.01, 0.04], p < 0.05) and externalizing symptoms (b = 0.03; 95% CI [0.01, 0.05], p < 0.001) among elementary students only. Student perceptions of school safety moderated the association between teacher distress and externalizing symptoms among elementary students, whereby the positive association was magnified among students reporting lower school safety.ConclusionsFindings from this study highlight the importance of concurrently addressing the mental health needs of educators and students. School safety represents a modifiable target for prevention and intervention efforts in schools that could serve to promote student mental health and mitigate potential risk factors in schools.