Background: Mindfulness Based Interventions (MBIs) for weight loss and overeating-related behaviours have recently gained popularity. Previous systematic reviews and meta-analyses included studies of variable quality, which hinders interpretation of results. This meta-analysis examined only randomised controlled trials (RCTs) comparing the efficacy of MBIs with control groups primarily encouraging either dietary or exercise-based behavioural change in individuals with overweight/obesity and/or binge eating disorder (BED). Methods: Using PRISMA guidelines, we systematically reviewed relevant articles in Medline, Psychinfo and EMBASE. Twelve eligible RCTs were identified, with three random-effects meta-analyses conducted on primary outcome measures of body mass (N = 11), mindfulness (N = 7) and BED symptoms (N = 3). Results: MBIs were more efficacious than control in increasing mindfulness scores and decreasing BED symptoms from pre-to post-treatment. However, they were no more efficacious than control in reducing body mass which may be attributed to variability in the duration of interventions. Based on intervention duration, exploratory cumulative meta-analyses revealed that while shorter interventions (i.e., 6 weeks) showed greater reductions in body mass compared to longer interventions (i.e., 24 weeks), longer interventions led to greater improvements in mindfulness scores and BED symptoms. Conclusions: These results highlight the potential of MBIs to improve obesity-related behaviours compared to lifestyle interventions, but their effects on short-term weight loss remain unclear. Future research with a rigorous methodology should consider long-term follow-ups including body mass and mindfulness-related outcome measures in order to establish the clinical potential of MBIs.