Aims and Objectives: To evaluate the effectiveness of school-based oral health educational (OHE) projects on oral health knowledge of government primary and intermediate students sponsored by King Salman Center for Children's Health (KSCCH) in Riyadh city, Saudi Arabia. Materials and Methods: OHE data of 2013–2014 semesters and 2014–2015 first semesters of government (n = 813) primary and intermediate school students were extracted from the KSCCH projects undertaken by Riyadh Elm University, Riyadh, Kingdom of Saudi Arabia. Student's oral health knowledge was assessed before and after OHE by administering pre/post-questionnaire. Total and topic-specific knowledge scores were reported and compared between gender, nationality, and educational level using nonparametric Mann–Whitney U-test and Wilcoxon's signed-rank test. Results: After the educational session, high and medium knowledge score categories showed an increase of 20.3% and 5.2%, respectively. On the contrary, low knowledge score category showed a decrease of 25.5% participants. This observed change was statistically significant (P ≤ 0.001). Comparison of correct responses between pretest and posttest showed statistically significant (P Conclusions: Educational projects sponsored by KSCCH demonstrated a definite positive impact on oral health knowledge of government primary and intermediate school students in Riyadh city, Saudi Arabia. For prolonged retention of oral health knowledge, repetition and reinforcement of OHE are necessary.