Purpose This study investigated the effects of nursing unit managers' authentic, transformational, and transactional leadership styles on positive psychological capital and turnover intention in advanced beginner-stage nurses (ABNs). Methods The study included 157 nurses with clinical experience ranging form more than one year to less than 3 years in three general hospitals. Data analysis was conducted using the SPSS/WINdows software version 26.0. Results Authentic, transformational, and transactional leadership styles of nursing unit managers increased the positive psychological capital of ABNs, thereby lowering their turnover intention. Additionally, the turnover intention of ABNs was negatively correlated with the authentic, transformational, and transactional leadership styles of a nursing unit manager and positive psychological capital. Positive psychological capital showed a mediating effect in the relationship between authentic, transformational, and transactional leadership styles of nursing unit manager and turnover intention of ABNs. Conclusion To reduce ABNs turnover, medical institutions and nursing organizations should focus on enhancing nursing unit managers’ transformational and authentic leadership styles. Moreover, as transactional leadership has been found to decrease the turnover intention among ABNs, nursing unit managers should carefully consider their responsibilities and resources allocation to provide conditional compensation support to nurses.