Epstein-Barr virus (EBV)-associated pediatric mature B-cell lymphoma is characterized by rapid progression, a poor prognosis, and a high relapse rate. However, research on this condition remains limited. This retrospective study analyzed its clinical features and prognostic factors in children. Kaplan-Meier analysis was performed to assess the impact of tumor EBV-encoded RNA (EBER)impact status on survival, and LASSO Cox regression was used to identify risk factors. The predictive performance of a model including the identified risk factors was assessed using calibration curves and receiver operating characteristic (ROC) curves. Tumor EBER status was significantly positively correlated with the EBV-DNA level (P < 0.05). EBER-positive pediatric patients presented elevated IgA levels, reduced IgG/IgM levels, decreased CD4 + T-cell counts, and increased CD8 + T-cell counts (P < 0.05). Compared with EBER-negative patients, EBER-positive patients had worse 5-year cumulative progression-free survival (PFS) (73.33%) and cumulative overall survival (OS) (78.30%) (P < 0.05). LASSO Cox regression analysis identified EBER (PFS HR 3.48, 95% CI 1.16-10.47, P = 0.027; OS HR 8.10, 95% CI 1.80-36.38, P = 0.006) and LDH (PFS HR 3.05, 95% CI 1.07-8.68, P = 0.037; OS HR 7.38, 95% CI 1.42-38.47, P = 0.018) as key prognostic markers. The model predicted 3-/5-year survival with high accuracy, with a C-index of 0.699 (95% CI: 0.558-0.841) for PFS and AUC (95% CI) values of 0.730 (0.575-0.886) and 0.691 (0.515-0.868). For OS, the C-index was 0.810 (95% CI: 0.669-0.952), and the AUC (95% CI) values were 0.805 (0.605-1.005) and 0.817 (0.618-1.015). Pediatric patients with EBV-associated mature B-cell lymphoma present distinct clinical and prognostic features that significantly influence the tumor immune microenvironment. The risk prognostic model based on tumor EBER status and LDH level reliably predicts outcomes in these patients.