We conducted an umbrella review to consolidate the evidence of adopting plant-based diets on anthropometric and cardiometabolic outcomes. Six electronic databases (CINAHL, EMBASE, PubMed, Scopus, the Cochrane Library, and Web of Science) were searched for systematic reviews with meta-analysis (SRMAs) published from each journal’s inception until 1 October 2022. Effect sizes from SRMAs and primary studies were pooled separately using random effects models. Overlapping primary studies were removed for primary studies’ analyses. Seven SRMAs representing 51 primary studies were included, suggesting significant benefits of plant-based diets on weight (−2.09 kg, 95% CI: −3.56, −0.62 kg,p= 0.01,I2= 95.6%), body mass index (−0.95 kg/m2, 95% CI: −1.26, −0.63 kg/m2,p= 0.002;I2= 45.1%), waist circumference (−2.20 cm, 95% CI: −0.08, 0.00 cm,p= 0.04;I2= 88.4%), fasting blood glucose (−0.11 mmol/L, 95% CI: −0.13, −0.09 mmol/L,p< 0.001,I2= 18.2%), and low-density lipoprotein cholesterol (−0.31 mmol/L, 95% CI: −0.41, −0.20 mmol/L,p< 0.001,I2= 65.6%). Changes in high-density lipoprotein cholesterol, triglycerides, and blood pressure were not statistically significant. Generally, plant-based diets were recommended to improve anthropometry, lipid profile, and glucose metabolism. However, findings should be interpreted with caution, because most of the reviews were rated to be of low credibility of evidence and were largely based on Western eating habits and traditions, which may limit the generalizability of findings.