Limited studies have reported about student nurses' level of competencies in performing leadership and management functions during their practicum and nursing internship in clinical areas. Also, safe and quality nursing practice is a major concern in clinical nursing practice settings. The aim of this study is to determine the relationship between the competencies of student nurses in performing leadership and management functions and their level of compliance to key performance indicators (KPIs) for patient safety outcomes at a private university in Nakhon Pathom, Thailand. This descriptive-correlational study includes 450 final-year students pursuing Bachelor of Nursing Science degrees (both Thai and International Programs) and are currently enrolled in nursing leadership and management courses, as well as professional nursing externship programs in a private university in Nakhon Pathom, Thailand. The findings of this study indicated that most of the Thai student nurses are competent (x̅ =3.23, SD±0.66) in performing nursing leadership and management functions. Moreover, the majority of student nurses demonstrated a moderate level of performance (x̅ =2.62, SD±0.96) of patient safety outcomes. Pearson correlation coefficient revealed a relatively high positive correlation between nursing leadership and management competencies and key performance indicators (KPIs) of patient safety outcomes among the respondents (r=0.96; p=0.000) at a significant level of 01. Further, these findings support the results of other previous studies indicating the level of competence of student nurses in performing nursing leadership and management functions. However, they contradict previous findings in which student nurses demonstrated a moderate level of performance to patient safety outcomes. Therefore, nursing schools must provide education, teaching, and training related to nursing leadership and management to student nurses as a way of preparing them to be competent to perform future nursing leadership roles.