This systematic review and meta-analysis examines the relationship between social support and turnover intention (TI) among clinical nurses, a workforce under increasing global pressure. The authors argue that social support — encompassing supervisor support and colleague support — serves as a significant protective factor against nurse TI, consistent with the buffering model of social support. Drawing on 38 cross-sectional studies involving 63,989 clinical nurses, sourced from seven international databases up to January 2024, the analysis found a statistically significant medium negative correlation between overall social support and TI (r = −0.278). Supervisor support (r = −0.119) and colleague support (r = −0.100) also showed significant negative correlations with TI, though with smaller effect sizes. Moderator analyses revealed that sample size and TI measurement tools significantly influenced the strength of the correlation, while nurse department, gender, data collection time, and social support measurement tools did not. The authors conclude that enhancing perceived social support among nurses may contribute to reducing turnover rates, though the exclusive reliance on cross-sectional studies precludes causal inference. Key insights: A statistically significant medium negative correlation exists between overall social support and nurse turnover intention (r = −0.278), based on 38 studies and 63,989 clinical nurses, with the relationship holding after trim-and-fill correction for publication bias (adjusted r = −0.195). Both supervisor support (r = −0.119) and colleague support (r = −0.100) are significantly negatively correlated with nurse TI, though effect sizes are small, suggesting social support type and source matter in understanding retention dynamics. Sample size and TI measurement tool selection significantly moderate the social support–TI correlation: studies with smaller samples (≤1,000) reported stronger correlations (r = −0.299) than larger-sample studies (r = −0.213), consistent with known publication bias patterns; TI measurement tool type produced the largest between-group variance in effect sizes. Practical takeaways: Organizational practices that strengthen supervisor-subordinate relationships and foster collegial teamwork among nurses are associated with lower observed turnover intention in the included studies, as both supervisor and colleague support dimensions demonstrated significant negative correlations with TI. The choice of TI measurement instrument introduces meaningful variation in observed effect sizes, with the three-item 1977 questionnaire yielding the smallest correlation (r = −0.150) and other tools yielding notably larger correlations (r = −0.329), indicating that instrument selection in nurse retention research warrants careful consideration for comparability.