Background The urinary tract dilation classification system has recently been developed to ensure a unified approach to describe urinary tract dilation in neonates and young infants. However, the predictive value of this system for surgical intervention or urinary tract infection (UTI) has not yet been evaluated in a meta-analysis. Objective This systematic review and meta-analysis aimed to evaluate the utility of a postnatal urinary tract dilation classification system for predicting surgical management or a UTI occurrence. Materials and methods As the urinary tract dilation classification system was introduced in 2014, we searched Embase and PubMed databases for studies published between January 2014 and December 2022. Original articles that reported surgical interventions or UTI episodes according to postnatal urinary tract dilation grades were included. The pooled odds ratio (OR) was calculated, using either the fixed-effects or random-effects model, given the lower urinary tract dilation grades as the base category. The quality of the included studies was evaluated using the Newcastle–Ottawa scale. Results Of the 285 articles reviewed, eight (comprising 2,165 children) were included in the analysis. The studies were of medium-to-high quality. Pooled analysis demonstrated that urinary tract dilation P3 (combined OR, 21.41; 95% confidence interval CI, 15.72–29.17) and urinary tract dilation P2–P3 (combined OR, 65.17; 95% CI, 33.08–128.38) were associated with surgical intervention. The urinary tract dilation P3 (combined OR, 2.11; 95% CI, 1.56–2.85) and urinary tract dilation P2–P3 (combined OR, 3.36; 95% CI, 2.43–4.63) were associated with UTI episodes. Conclusion The postnatal urinary tract dilation classification system is useful for predicting the need for surgical management and UTI episodes in infants with hydronephrosis.