Background: Active management of third stage of labor (AMTSL) is a vital possession for nurses to prevent postpartum hemorrhage (PPH). Internships offer carefully planned, monitored work experience which allows the opportunity to apply knowledge and skills in a professional setting. Aim: To evaluate the effect of competency-based education on intern nursing students' performance regarding active management of third stage of labor. Design: A quasi-experimental design. Sample: A convenient sample of 60 female intern nursing students who practiced their internship year in the Faculty of Nursing, Mansoura University in the academic year (2021/2022). Setting: The delivery unit at Mansoura University Hospital, Egypt. Tools: A self-administered questionnaire, AMTSL practical observational checklist, AMTSL attitudes assessment sheet, and satisfaction Likert scale. Results: Statistically significant improvements in intern students' knowledge, attitudes, and practical skills regarding AMTSL immediately post-intervention and follow-up were found. Furthermore, total intern students' knowledge and practices pre-intervention, immediately-post, and follow-up were positively correlated. About three-quarters of the intern students were satisfied with the clinical training method post-intervention. Conclusion: Competency-based education was effective in improving the knowledge, attitudes, and practices of intern nursing students regarding AMTSL which translated into higher satisfaction scores. Recommendations: Continuous competency-based education should be conducted for students to improve their knowledge, attitudes, and practices regarding AMTSL.