Purpose The purpose of this paper is to analyze whether and how employees’ proactive personality is related to work engagement. Drawing on job demands-resources theory, the study proposes that this relationship is moderated by a three-way interaction between proactive personality × transformational leadership × growth mindset. Design/methodology/approach The study is based on survey data from 259 employees of an internationally operating high-tech organization in the Netherlands. Findings In line with prior studies, support is found for positive significant relationships of proactive personality and transformational leadership with engagement. Additionally, transformational leadership is found to moderate the relationship between proactive personality and work engagement, but only when employees have a growth mindset. Originality/value The study advances the literature that investigates the proactive personality-engagement relationship. Specifically, this study is the first to examine a possible three-way interaction that may deepen the insights for how proactive personality, transformational leadership and growth mindset interact in their contribution to work engagement.