Mindfulness has been shown to have varied associations with different forms of motivation, leading to a lack of clarity as to how and when it may foster healthy motivational states. Grounded in self-determination theory, the present study proposes a theoretical model for how mindfulness supports different forms of human motivation, and then tests this via meta-analysis. A systematic review identified 89 relevant studies (N = 25,176), comprising 104 independent data sets and 200 effect sizes. We used a three-level modeling approach to meta-analyze these data. Across both correlational and intervention studies, we found consistent support for mindfulness predicting more autonomous forms of motivation and, among correlational studies, less controlled motivation and amotivation. We conducted moderation analyses to probe heterogeneity in the effects, including bias within studies. We conclude by highlighting substantive and methodological issues that need to be addressed in future research in this area.