The inadequate quality of care provided to mothers and newborns is the primary cause of the high rates of maternal and neonatal mortality, likely due to healthcare providers lacking skills in managing the initial stage of labor. In order to guarantee high-quality nursing care, competencies fill the gap between education and practice. The aim of this research was to evaluate the effect of competency-based education on maternity nurses' performance and quality of care regarding management of first stage of labor. Design: A quasi-experimental research design (One-Group, Time series quasi-experimental design). Setting: The research was conducted at obstetrics and gynecological emergency department (labour unit) at Benha University hospitals in Qaliubya governorate, Egypt. Sample: A convenient sample of 53 maternity nurses. Data collection tools: Four tools were used to collect data: A structured interviewing questionnaire (Personal characteristics of maternity nurses and Maternity nurses' knowledge questionnaire), Observational Practical Checklists, Nurse competency scale and Quality of Nursing Care Scale. Results: There was a statistical significant improvement in maternity nurses' total knowledge, total practices, total competency and total quality of care regarding management of the first stage of labour at immediately post-intervention and follow up phases compared to pre-intervention phase. It was revealed that total mean scores of studied nurses' knowledge, practices, competency and quality of care were higher at immediately post-intervention and follow up phases compared to pre-intervention phase. Conclusion: The implementation of competency based education was effective in improving maternity nurses' total knowledge score, total practices score and total quality of care regarding management of the first stage of labour. Recommendation: It was recommended that ongoing competency-based education is essential for maternity nurses to improve their knowledge, practices, competency and quality of care regarding management of labour.