The concept of growth mindset--an individual's beliefs that basic characteristics such as intelligence are malleable--has gained immense popularity in research, the media, and educational practice. Even though it is assumed that teachers need a growth mindset and that both teachers and their students benefit when teachers adopt a growth mindset, systematic syntheses of the potential advantages of a growth mindset in teachers are lacking. Therefore, in this article, we present the first meta-analysis on teachers' growth mindset and its relationships with multiple outcomes (50 studies, 81 effect sizes; N = 19,555). Multilevel analyses showed a small effect across outcomes. Statistically significant small-to-typical positive associations between teachers' growth mindset and their motivation in terms of self-efficacy and mastery goals were observed in subgroup analyses. No statistically significant relationships were found with teachers' performance-approach goals, teachers' performance-avoidance goals, teachers' performance on achievement tests, or student achievement. Teachers' growth mindset was related to instructional practices in terms of mastery goal structures but unrelated to performance goal structures. Moderator analyses indicated that the dimensionality of the mindset measure (recoded from a fixed mindset to a growth mindset measure vs. assessed as a growth mindset), item referent and content of the mindset measure, publication status (published vs. unpublished), world region, educational level, and study quality influenced the strengths of some of the relationships. Overall, our findings extend knowledge about teachers' mindset and add to the evidence base on teacher characteristics and their links to relevant outcomes.