Aim: Training and employment of competent nurses are among the priorities of nursing. This study was conducted to develop a valid and reliable measurement tool for determining the competency perceptions of senior nursing students. Methods: The methodological study was carried out with 372 senior nursing students who studied in nursing departments of two universities in Istanbul between January and March 2018. The item pool of the scale was created with the learning outcomes within the scope of the “Quality and Safety Education for Nurses” project in the United States of America. After content validity, the scale consisted of 55 items and six main dimensions. Data were collected using a questionnaire, including a personal information form and the Nursing Competency Perception Scale. Data analysis was performed using descriptive statistics, exploratory and confirmatory factor analysis, Pearson correlation analysis, t-test in dependents groups, and Cronbach’s alpha coefficient. Results: As a result of exploratory and confirmatory factor analysis, 39 items with a 6-factor structure were retained to form the Nursing Competency Perception Scale. These factors showed senior nursing students’ competency perceptions in patient-centered care, teamwork and collaboration, evidence-based practice, quality improvement, safety, and informatics. Cronbach’s alpha coefficient was between 0.77 and 0.90. There was no statistical difference between the test–retest measurements in the six dimensions (P > .05). Pearson correlation coefficients from 0.71 to 0.90 were found in the six main dimensions (P < .001). Conclusion: The Nursing Competency Perception Scale is a valid and reliable tool for determining the competency perceptions of senior nursing students and new graduate nurses with no professional experience.