OBJECTIVES: To examine the effect of mindfulness interventions on cognitive tasks in healthy older adults and older adults with diagnoses of mild cognitive impairment (MCI) or dementia. METHODS: Three-level meta-analysis and systematic review of 30 published randomized-controlled trials. RESULTS: Mindfulness interventions provided a small, yet significant positive effect on cognition compared to a control group (average weighted Hedges' g = 0.36, 95% confidence interval [CI] [0.06-0.65]). Attention (g = 0.22, 95% CI = [0.09, 0.35]), long-term memory (g = 0.32, 95% CI = [0.08, 0.56]), and visuospatial processing (g = 0.22, 95% CI = [0.10, 0.34]) all showed significantly meaningful changes regardless of cognitive status of the participants. There was no evidence for publication bias. Healthy older adults showed higher effect sizes than those with MCI (g = 0.27, 95% CI = [0.11, 0.43], vs. (g = -0.09, 95% CI = [-0.35, 0.17], respectively). Otherwise, there were no significant moderating effects of age, marital status, education, region, intervention type, length, number of sessions, adherence, or gender on effect size. Moderator analyses within cognitive domains suggest that focused attention practices might be the best for improving cognition. Lastly, meditation interventions seem to work as effectively as other mind-body interventions, but not as effectively as other interventions to improve cognitive functioning in older adults. DISCUSSION: Mindfulness interventions appear to be a useful tool for improving cognitive functioning in older adults.