A systematic review and meta-analysis of observational studies was performed to assess the dose-response association of serum vitamin D concentration with MetS risk. A systematic literature search was conducted in PubMed, MEDLINE, and EMBASE through February, 2020 and the references of relevant articles were reviewed. A random-effects model was used to estimate the summary odds ratio/relative risk and 95% confidence interval (CI). Heterogeneity among studies was evaluated with I2 statistic. In total, 25 observational studies (19 cross-sectional studies, three case-control studies, and three cohort studies) were included in the meta-analysis. The pooled estimates (95% CI) for MetS per 25-nmol/L increment in serum vitamin D concentration were 0·80 (95% CI: 0·76, 0·84, I2 = 53·5) in cross-sectional studies, 0·80 (95% CI: 0·68, 0·92, I2 = 78·0) in cohort studies and 0·97 (95% CI: 0·88, 1·07, I2 = 45·4) in case-control studies. Study design (P = 0·01), quality assessment (P = 0·08) and alcohol adjustment (P = 0·03) contributed to heterogeneity. There was no indication of small-study effects for the dose-response meta-analysis of serum vitamin D concentrations and MetS. Serum vitamin D concentration was inversely associated with the risk of MetS in both cross-sectional studies and prospective cohort studies.