Research has shown that unsociability, reflected as a personal choice, is not necessarily associated with socio-emotional problems in Western countries. However, the associations between unsociability and peer problems are consistently evident in Chinese culture, yet the strength and direction in these associations are mixed. The present study aimed to examine whether unsociability is associated with peer problems and explored the potential moderators among the associations. A meta-analysis was conducted using publications that measured unsociability and peer problems. A total of 21 articles involving 43 effect sizes from 12,696 Chinese children and adolescents were included. The results revealed that (1) unsociability was positively associated with peer problems (r = 0.32, p < 0.001) among children and adolescents. (2) Informants (i.e., self-reports, peer nominations, teacher ratings, and parent ratings) and living areas (i.e., urban, suburban, and rural areas) significantly moderated the associations between unsociability and peer problems. Specifically, the associations were stronger for peer-nominated unsociability, self-reported peer problems, and samples in suburban areas. These findings shed light on unsociability linked to higher levels of peer problems among Chinese children and adolescents. Still, the influences are unique to peer problems and moderated by both data sources and environmental factors.