While job insecurity has a wide range of negative effects on employees’ work attitudes and behaviors, scholars still know little about its impact on leaders. Drawing from conservation of resources theory, we developed and tested a theoretical model that links job insecurity and transformational leadership behavior. This model explores the mediating role of emotional exhaustion and the moderating role of leaders’ trait mindfulness in influencing the mediation. Results from data that were collected at two time points from 161 leader–follower dyads in various Chinese organizations showed that job insecurity is negatively related to transformational leadership behavior through increased emotional exhaustion. Moreover, the positive relationship between job insecurity and emotional exhaustion as well as the negative indirect effect of job insecurity on transformational leadership behavior via emotional exhaustion are weaker for leaders with high levels of trait mindfulness. Implications for research and practice are discussed.