(1) Background: Given that the most effective dose, optimal type, and most beneficial population for improving sleep with mindfulness-based movement (MBM) remains unknown, we conducted a systematic review and meta-analysis with moderator analysis of randomized controlled trials (RCTs) to assess these effects. (2) Methods: Three electronic databases (PubMed, Web of Science, and EBSCO) were systematically searched for RCTs published through August 2021 for analysis. The risk of bias of the included studies was assessed with Review Manager 5.3, and the meta-analysis was performed in Stata 16.0. (3) Results: A meta-analysis of 61 RCTs with 2697 participants showed that MBM significantly improved sleep quality compared to controls (SMD = -0.794; 95% CI: -0.794 to -0.994, p < 0.001, I-2 = 90.7%). Moderator analysis showed that a long-term MBM (SMD = -0.829; 95% CI: 0.945 to 0.712; p < 0.001) had a larger effect size on sleep than a short-term MBM (SMD = -0.714; 95% CI: 0.784 to 0.644; p < 0.001). Practicing at least twice per week (SMD = -0.793; 95% CI: -0.868 to -0.718; p < 0.001) was more effective compared to practicing once per week (SMD = -0.687; 95% CI: -0.804 to -0.570; p < 0.001). Studies with a total intervention time of more than 24 h also revealed better sleep quality improvement (SMD = -0.759; 95% CI: -0.865 to -0.653; p < 0.001). In addition, the healthy population and older adults gained more from MBM than the patients and younger adults. (4) Conclusions: MBM can effectively improve subjective sleep quality, and the optimal intervention dose of MBM can be utilized in future intervention studies to treat or improve sleep disturbance (MBM more than twice a week for more than three months, with a total intervention time of more than 24 h).