We performed this systematic review and meta-analysis to evaluate observational studies assessing the association between ultra-processed food (UPF) consumption and the risk of overweight, obesity, and abdominal obesity in the general population. We searched the databases PubMed/MEDLINE, Scopus, Embase, and ISI Web of Science from inception until December 2020. Data were extracted from 12 studies (nine cross-sectional and three cohort studies). Odds ratio (OR) were pooled using a random-effects model. UPF consumption was associated with an increased risk of obesity (OR = 1.55; 95% CI: 1.36, 1.77; I² = 55%), overweight (OR = 1.36; 95% CI: 1.14, 1.63; I² = 73%), and abdominal obesity (OR = 1.41; 95% CI: 1.18, 1.68; I² = 62%). Furthermore, every 10% increase of UPF consumption in daily calorie intake was associated with a 7%, a 6%, and a 5% higher risk of overweight, obesity, and abdominal obesity, respectively. Dose-response meta-analysis of cross-sectional studies showed a positive linear association between UPF consumption and abdominal obesity. There was also a positive linear association between UPF consumption and risk of overweight/obesity in the analysis of cross-sectional studies and a positive monotonic association in the analysis of cohort studies. Our study suggests that UPF consumption is associated with an increased risk of excess weight or abdominal obesity.