<p>Many theoretical explanations have been used to explain whether fear of missing out (FoMO) arises from a lack of social connections or from too many social connections. However, the correlation between (dis)connectedness and FoMO remains unclear. To address this gap, we conducted a meta-analysis of 104 research findings from 99 independent studies (<i>N</i> = 54764) to systematically examine the nature of the associations between perceived disconnectedness (loneliness and social isolation), connectedness (belongingness and social support), and FoMO. The meta-analysis produced three main findings. First, the results show that loneliness and social isolation positively correlate with FoMO, whereas there is no significant relationship between belongingness, social support, and FoMO. Second, social support type moderate the relationship between social support and FoMO. Third, the correlation between loneliness and FoMO can be explained by variations in cultural context, including uncertainty avoidance, intellectual autonomy, harmony, and geographical area. On the basis of the meta-analysis results theoretical implications for future research and practical suggestions for psychological interventions for FoMO are discussed.</p>