Potentially inappropriate prescribing in older adults can lead to adverse health outcomes and worsened health-related quality of life. This meta-analysis estimated the prevalence of potentially inappropriate prescribing in older adults to be 3.3%, and estimated that potentially inappropriate prescribing explains 7.7 to 17.3% of adverse outcomes affecting older adults in primary care. Interventions to prevent potentially inappropriate prescribing should be prioritized as a key strategy to reduce medication-related harm along older adults in primary care settings.