Objective To assess the predictive value of the Pediatric Sequential Organ Failure Assessment (pSOFA), Pediatric Index of Mortality 3 (PIM-3), Pediatric Risk of Mortality IV (PRISM IV), Phoenix Sepsis Score (PSS), Phoenix Sepsis Score-8 (Phoenix-8), the ratio of neutrophil count to lymphocyte and platelet count (N/LPR), and a nomogram constructed from these factors for 28-day mortality in children with sepsis. Methods A retrospective analysis was conducted on 267 children with sepsis admitted to the Pediatric Intensive Care Unit of the Third Affiliated Hospital of Zhengzhou University from January 2017 to January 2025. Patients were categorized into a survival group (n=208) and a death group (n=59). Differences in clinical indicators between the two groups were compared. Univariate and multivariable logistic regression were used to identify independent risk factors for 28-day mortality and to construct a nomogram. Predictive performance was evaluated using receiver operating characteristic curves, calibration curves, and decision curve analysis. Results pSOFA, PIM-3, PRISM IV, PSS, Phoenix-8 scores, N/LPR, and lactate levels were significantly higher in the death group than in the survival group (P<0.05). Multivariable logistic regression identified pSOFA, PRISM IV, PSS, and N/LPR as independent risk factors for 28-day mortality. The nomogram based on these factors achieved the area under the receiver operating characteristic curves of 0.940 in the training group and 0.911 in the validation group, with good calibration according to the Hosmer-Lemeshow test (P>0.05), and decision curve analysis indicated good clinical applicability. Conclusions A nomogram incorporating pSOFA, PRISM IV, PSS, and N/LPR shows good predictive value for 28-day mortality risk in children with sepsis.