Mindfulness-based interventions (MBIs) are associated with increased psychological wellbeing. The literature suggests that individuals exposed to adverse childhood experiences (ACEs) may benefit greatly from MBIs. However, research has tended to focus on universal MBIs for this population with less attention on the effectiveness of targeted approaches. Moreover, there is growing concern regarding the methodological rigor of MBI research. This systematic mixed studies review (SMRS) reports the effectiveness of MBIs for improving mental health and cognition among individuals with ACE histories. Additionally, the review reports the quality and rigor of the included research. Systematic searches of PsycInfo, EMBASE, MEDLINE, ProQuest Dissertations and Theses, ProQuest Social Science database and the Child Development and Adolescent Studies database were conducted. Results were screened and data were extracted then synthesized using a data-based convergent synthesis design. Thirteen studies were included in the final review. Six prominent themes emerged. Themes indicated that MBIs were effective for improving mental health and cognition for individuals with ACEs. For example, improvements in mood and anxieties, as well as a better ability to manage emotions. Shortcomings in the quality of MBI research included lack of reporting of methodological details (e.g., randomization procedures) and not systematically reporting adverse event evaluations. Recommendations are made for future research to strengthen the evidence base for MBIs for individuals with ACEs.