Literature suggests that occupational stress is associated with a higher risk of metabolic syndrome; yet less is known whether other sources of stress have similar effects. This review aims to examine whether the relationship between psychological stress and metabolic syndrome differs by sources of stress. Three databases (PubMed, Web of Science, and CINAHL) were searched for eligible articles; meta-analyses were conducted using the random effects model. After controlling for covariates, adults in the high-stress groups had 45% higher chance of having metabolic syndrome than adults in the low-stress groups (odds ratio [OR] = 1.450; 95% confidence interval [CI], 1.211-1.735; P < .001). The subsequent meta-analysis based on cross-sectional studies suggested that occupational stress showed the strongest effect (OR = 1.692; 95% CI, 1.182-2.424; P = .004), while perceived general stress showed the weakest effect (OR = 1.217; 95% CI, 1.017-1.457; P = .032). Unfortunately, there is a lack of longitudinal studies for subsequent meta-analysis based on sources of stress. There is a need for continued research to examine the long-term relationship between different sources of stress and the risk of metabolic syndrome. Traditional recommendations for preventing metabolic syndrome (eg, low-fat diet and exercise) may not achieve the best outcome if clinicians overlook patients' psychosocial stress.