ObjectivesTo assess the impact of an oral health education and preventive program (OHEPP) for pediatric cancer patients.MethodsThis was a single‐arm study with 27 children and adolescents undergoing antineoplastic treatments. Patients were followed up for 10 weeks, and their oral health conditions were evaluated using the Modified Gingival Index (MGI), Visible Plaque Index (VPI), and the modified Oral Assessment Guide (OAG). Audiovisual resources, storytelling, and ludic instruments were used to provide oral health education to patients and parents/caregivers.ResultsThe patients’ mean age was 9.41 (±4.49) years, and acute lymphoblastic leukemia was the most prevalent diagnosis (22.2%). Mean MGI and VPI values were 0.82 (±0.59) and 54.11% (±19.92%) at baseline and 0.33 (±0.29) and 19.83% (± 11.47%) after 10 weeks, respectively (p < .05). The mean OAG score was 9.51 (±2.54) and 36 cases (19.8%) of severe oral mucositis (SOM) were documented. Patients with higher MGI were more likely to develop SOM.ConclusionThe OHEPP had a positive impact on pediatric patients undergoing cancer therapy by improving their periodontal health, reducing biofilm accumulation, and preventing the development of OM lesions.