Pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) can be used in pediatric patients. This study assessed the safety and efficacy of PEG-rhG-CSF as a primary prophylactic drug against neutropenia after chemotherapy in pediatric patients with solid tumors or non-Hodgkin lymphoma (NHL).This phase II study (between October 2020 and March 2022) enrolled pediatric patients with solid tumors or NHL treated with high-intensity chemotherapy and with grade ≥3 myelosuppression for at least 14 days during chemotherapy. Prophylactic PEG-rhG-CSF was given at 100 μg/kg body weight (maximum total dosage of 6 mg) once 24-48 h following chemotherapy for two cycles. The primary endpoint was the incidence of PEG-rhG-CSF-related adverse events (AEs). The key secondary endpoints were the rates of grade 3/4 neutropenia and febrile neutropenia (FN).This study included 160 pediatric patients with a median age of 6.22 (0.29, 18.00) years. Fifty-eight patients (36.25%) were diagnosed with sarcoma. AEs potentially related to PEG-rhG-CSF included bone pain (n = 32), fatigue (n = 21), pain at the injection site (n = 21), and myalgia (n = 20). The rates of grade 3/4 neutropenia and FN during treatment were 57.28% and 29.45%, respectively.PEG-rhG-CSF is well tolerated and effective in pediatric patients with solid tumors or NHL. These findings should be substantiated with further trials.ClinicalTrials.gov identifier: NCT04547829.© 2023 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.