BACKGROUND: Animal-assisted therapy (AAT) can ameliorate diverse health problems in older adults. However, applications of AAT have been limited because of the lack of intervention guidelines for older adults. AIMS: This study aimed to explore applications of AAT to older adults, analyze its health effects, and provide evidence for future interventions. METHODS: A systematic review and meta-analysis were conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Data were analyzed based on both a narrative synthesis and a meta-analysis specifically for depression. RESULTS: A total of 47 studies were selected for analysis. About 45% focused on older adults with diseases such as dementia, and 57.4% selected dog(s) as an intervention animal. About 34.0% delivered interventions once a week, and the behavioral outcome domain was the most frequently investigated. The meta-analysis showed that the effect sizes of the AAT group were -1.310 (95% CI [-1.900, -.721]). LINKING EVIDENCE TO ACTION: This review provides evidence for AAT as an intervention in the physiological, psychosocial, cognitive, and behavioral domains of older adults. When planning interventions for older adults, nurses should consider intended health outcomes, appropriate therapeutic animals, and the consequent intervention contents.