This meta-analysis was conducted to systematically evaluate the prognostic role of the Naples prognostic score (NPS) in patients with gastrointestinal (GI) cancers. A comprehensive literature search of several major databases was performed for studies published until October 16, 2022. Hazard ratios (HRs) with 95% confidence intervals (CIs) were extracted and pooled by fixed-effects or random-effects models to analyze the associations between the NPS and overall survival (OS), cancer-specific survival (CSS), and recurrence-free/disease-free survival (RFS/DFS) in GI cancers. Thirteen studies were included in the meta-analysis. Pooled results indicated that a high NPS predicted poor OS (HR = 2.28, 95% CI: 1.90-2.74, p < 0.001), CSS (HR = 2.77, 95% CI: 2.10-3.66, p < 0.001), and RFS/DFS (HR = 2.77, 95% CI: 2.26-3.40, p < 0.001). For OS-related and RFS/DFS-related studies, subgroup analyses showed that a high NPS was significantly associated with poor OS and RFS/DFS irrespective of NPS group, calculation of the NPS, and tumor type. In the study that focused on CSS, subgroup analyses by NPS group and calculation of the NPS revealed similar results. The NPS may represent an effective prognostic indicator in patients with GI cancers.