BACKGROUNDGlobally, loneliness is a growing public health concern associated with poor mental and physical health among older adults. Therefore, we performed a meta-analysis to explore the prevalence of loneliness and associated risk factors among older adults across six continents.METHODSWeb of Science, PubMed, Embase, CINAHL, Cochrane Library, and references lists were comprehensively searched until April 2024. Data analysis was performed using Logit Transformation model in R-Software for pooled prevalence and DerSimonian-Lard random-effects model in Comprehensive Meta-Analysis for associated factors of loneliness. Heterogeneity was quantified by I2 and τ2 statistics. The funnel plot and Egger's regression test assessed publication bias.RESULTSA total of 70 studies with 462,083 older adults were included. The pooled prevalence of loneliness was 26 % (95 %CI, 23 %-30 %) with 38 % for North America, 34 % for Africa, 32 % for Asia and South America, 23 % for Europe, and 13 % for Oceania. Cognitive impairment (2.98; 95 %CI, 1.30-6.81), poor health (2.35; 95 %CI, 1.59-3.45), female (1.92; 95 %CI, 1.53-2.41), depression (1.74; 95 %CI, 1.40-2.16), widowed (1.67; 95 %CI, 1.13-2.48), single (1.51; 95 %CI, 1.06-2.17), institutionalization (2.95; 95 %CI, 1.48-5.88), rural residency (1.18; 95 %CI, 1.04-1.34) were associated with increased risk of loneliness. Being married (0.51; 95 %CI, 0.31-0.82), male (0.55; 95 %CI, 0.43-0.70), and non-institutionalization (0.34; 95 %CI, 0.17-0.68) were associated with lower risk of loneliness.CONCLUSIONApproximately, three among ten older adults aged ≥ 60 years are lonely worldwide. Early detection, prevention, and management of loneliness among older adults should consider diverse needs using gender-specific approaches.