Introduction: Thrombosis in pediatric patients is a growing concern in pediatrics. Venous Thromboembolism has become an increasingly recognized condition, particularly among hospitalized children. Objectives: This study aimed to evaluate the effect of a clinical practice guidelines intervention program on pediatric nurses' adherence to preventing venous thromboembolism. Methods: A quasi-experimental design with one group pre-test and post-test was used. The study was conducted at coronary, medical, and surgical pediatric intensive care units at El-Demerdash Children's Hospital and Abu El-Reesh Japanese Children's Hospital. A convenience sample of 156 pediatric nurses. Data were collected using three tools: Characteristics of pediatric nurses, nurses’ knowledge questionnaire, and observational practice checklist. Results: The total mean scores of nurses’ knowledge and practices post-implementation of the clinical practice guidelines intervention program significantly improved (44.62 ± 7.818 and 30.23 ± 2.905, respectively) compared with pre-program total mean scores (27.50 ± 11.486 and 27.22 ± 5.506, respectively), demonstrating the program's effectiveness. There was a strong positive significant correlation post-implementation (r = 0.538, p = 0.021) between the total level of nurses' knowledge and practices. Conclusions: The clinical practice guidelines intervention program significantly improved nurses' adherence to preventing venous thromboembolism, supporting the study hypothesis. Therefore, it is recommended that, incorporating venous thromboembolism risk assessment and prophylaxis into hospital protocols is essential for enhancing patient safety and ensuring compliance with established guidelines.