The purpose of this research was to explore nurses' mentorship, mentors' basic psychological needs satisfaction and transformational leadership. Moreover, this study evaluated the moderating role of a protégé's mindfulness.Previous research had only focused on the benefits that protégés reaped from the mentoring relationship, neglected the mentor's benefits.We conducted an analysis of a cross-sectional sample comprising 366 frontline nurses in China. Descriptive, correlation and regression analyses were conducted using SPSS 22.0. Mediating, moderating and conditional process analyses were conducted using Process Macro 3.3.Mentorship is associated with mentors' transformational leadership through the satisfaction of their basic psychological needs (β = .13, 95% confidence interval [CI]: [0.05, 0.23]). The indirect association of mentorship and transformational leadership is stronger for protégés with low mindfulness levels (β = -.05, 95% CI: [-0.08, -0.02]).The establishment of healthy associations between mentors and protégés facilitates the fulfilment of the mentors' basic psychological needs, enhancing the former's transformational leadership, especially for protégés with low mindfulness levels.Mentors should provide more meaningful knowledge about the organisation and protégés' career path, obtain information to help tailor the advice and put more energy into building trust-based relationships with protégés.