There is a paucity of pooled synthesized data on the epidemiology of neonatal acute kidney injury (AKI). Our objective with this study is to systematically assess the worldwide incidence of AKI in neonates. We searched 3 electronic databases (Embase, PubMed, Web of Sciences) from January 2004 to December 2022 without language restrictions. We included cohort and cross-sectional studies that reported the incidence of AKI or associated mortality in neonates. Eligible studies had at least 10 participants and used standard criteria (Acute Kidney Injury Network/Pediatric Risk, Injury, Failure, Loss, End Stage Renal Disease (pRIFLE)/ Kidney Disease Improving Global Outcomes) to define AKI. Two authors independently retrieved data on demographic characteristics, clinical setting, and outcomes (incidence and AKI-associated mortality) using a semi-structured proforma and assessed the risk of bias. We used a random-effects meta-analysis to calculate pooled estimates with 95% confidence intervals. We included 201 studies (98 228 participants) from 45 countries. The incidence of any stage AKI was 30% (95% confidence interval 28-32), and that of severe AKI was 15% (14-16). Overall, AKI-associated mortality was 30% (27-33). The odds of mortality were higher (odds ratio 3.4; 2.9-4.0) in neonates with AKI compared with those without AKI. We found that perinatal asphyxia, sepsis, patent ductus arteriosus, necrotizing enterocolitis, and nephrotoxic medications were significant risk factors for AKI. Significant heterogeneity in the pooled estimates was a limitation of this study. AKI was observed in one-third of the neonates and was associated with increased risk of mortality. The incidence of AKI was almost similar in neonates with perinatal asphyxia and sepsis, but mortality was higher in the former group.