Background: Clinical competency of internship nursing students is a vital element for hospitals' survival to ensure the quality of care provided and patients' satisfaction. COVID-19 pandemic had great effect on students learning process all over the world. The Aim of the current study was to evaluate the effect of a mobile-based learning intervention on the clinical competence of the internship-nursing students during the COVID-19 pandemic. A Quasi-experimental research design was applied. A convenient sample of all available internship-nursing students who were training at five hospitals in Mansoura city, Egypt were included (248). The Clinical competence Questionnaire (CCQ) was used to evaluate the clinical competence. Results revealed that there was marked increase in total competence rate of the studied internship-nursing students; high competence rate represents 96.8% in post-test instead of 56.9% in pre-test. Conclusion: During COVID-19 Pandemic, the mobile-based learning intervention had a high positive effect on the clinical competence of the internship-nursing students. The results of the study recommended including the distant learning methods in the learning process of the nursing students.