<p>Loneliness is increasingly recognized as a global public health concern, yet cross-national evidence remains limited. Using data from the 2023–2024 Gallup World Poll, this study provides a globally representative description of loneliness across 148 countries (<i>N</i> = 218,048). Over one in five adults reported feeling lonely, with prevalence highest in low-income countries and Sub-Saharan Africa. Multivariate analyses identified several predictors of lower loneliness, such as better health, higher education, larger household size, and employment, though their associations varied by context. Loneliness was also associated with lower subjective well-being, more frequent negative emotions, and stronger migration intentions. These patterns were most pronounced in high-income and more developed regions, where loneliness appeared more psychologically burdensome despite lower prevalence. Overall, the findings highlight loneliness as a universal but context-sensitive experience, suggesting the need for policies that consider both structural and psychosocial factors to promote social connection and emotional well-being worldwide.</p>