Teachers report high levels of occupational stress, which is associated with teacher turnover and potential negative consequences for students. Mindfulness-based interventions (MBIs) may improve the protective factors that buffer educators against occupational stress. Although previous meta-analytic reviews synthesized the effects of MBIs for healthy and clinical samples of adults, this study was the first to synthesize the effects of MBIs for teachers (grades pre-K through 12). A total of 347 effect sizes from 29 studies (N = 1,493) were synthesized using metaregression with robust variance estimation. Overall, MBIs had a medium treatment effect on teacher outcomes (g = 0.601, SE = 0.089). Visual and statistical evidence of publication bias suggested this estimate may be positively biased. Three potential study-level moderators for overall effects were also examined, but none were statistically significant. MBIs were associated with small-to-medium positive effects on therapeutic processes and therapeutic outcomes. MBIs had the smallest effects on measures of classroom climate and instructional practices. Overall, findings were similar to other meta-analytic reviews of MBIs for nonclinical adult populations and working professionals. The literature on MBIs for teachers appears to have similar gaps as research on MBIs for adults (e.g., Davidson & Kaszniak, 2015), including the primary use of self-report measures, the lack of active treatment comparisons, and rare reporting of treatment fidelity data. Directions for future research and implications are discussed.