Objectives Evaluation of the effectiveness of Photobiomodulation(PBM) for chemotherapy‐induced oral mucositis (OM) in leukemic children. Materials and methods A randomized controlled clinical study including forty‐four leukemic children diagnosed with chemotherapy‐induced OM at the Hematology/Oncology inpatient unit at Alexandria University Children's Hospital, Alexandria, Egypt. Patients were randomly assigned to either the control or test groups with a 1:1 ratio. The control group received conventional symptomatic treatment, while the test group was treated with PBM in addition to the symptomatic treatment. The response to both treatment modalities was evaluated according to the reduction of pain and lesions severity from baseline to 5, 10, and 14 days after treatment. Results A significant reduction of pain was recorded on day 10 in the test group compared to the control group (p < 0.001). There was also a significant decline in the OM grades between the two groups on day14 (p = 0.003). No adverse events were reported. Conclusions The use of PBM along with the conventional treatment was effective in reducing pain and in the recovery of OM lesions in children receiving chemotherapy for the treatment of ALL. It was also safe and applicable to children.