Military veterans report high rates of psychiatric and physical health symptoms that may be amenable to mindfulness-based interventions (MBIs). Inconsistent prior findings and questions of fit between MBIs and military culture highlight the need for a systematic evaluation of this literature. To quantify the efficacy and acceptability of MBIs for military veterans. We searched five databases (MEDLINE/PubMed, CINAHL, Scopus, Web of Science, PsycINFO) from inception to October 16th, 2019. Randomized controlled trials (RCTs) testing MBIs in military veterans. Twenty studies (k = 16 unique comparisons, N = 898) were included. At post-treatment, MBIs were superior to non-specific controls (e.g., waitlist, attentional placebos) on measures of posttraumatic stress disorder (PTSD), depression, general psychological symptoms (i.e., aggregated across symptom domains), quality of life / functioning, and mindfulness (Hedges' gs = 0.32 to 0.80), but not physical health. At follow-up (mean length = 3.19 months), MBIs continued to outperform non-specific controls on general psychological symptoms, but not PTSD. MBIs were superior to specific active controls (i.e., other therapies) at post-treatment on measures of PTSD and general psychological symptoms (gs = 0.19 to 0.25). Participants randomized to MBIs showed higher rates of attrition than those randomized to control interventions (odds ratio = 1.98). Several models were not robust to tests of publication bias. Study quality and risk of bias assessment indicated several areas of concern. MBIs may improve psychological symptoms and quality of life / functioning in veterans. Questionable acceptability and few high-quality studies support the need for rigorous RCTs, potentially adapted to veterans. •Mindfulness-based interventions (MBIs) produce psychological benefits in veterans.•MBIs may slightly outperform other active interventions.•Veterans are more likely to drop out of MBIs than active control conditions.•Large-scale randomized trials with follow-up assessment are needed.