<p>In the current fiercely competitive market landscape, leaders and employees within organizations are confronted with substantial pressures emanating from the industry. To bolster organizational performance, the prevalence of leader workaholism has become increasingly evident. However, the literature does not reach a consensus on whether leader workaholism can effectively enhance subordinates’ task performance. In view of this, based on the Conservation of Resources Theory, this study investigates the ambivalent effects of leader workaholism on the task performance of subordinates, as well as the boundary conditions that delineate its effects. Through a scenario experiment (<i>N</i> = 148) and a multi-wave and multi-source survey (<i>N</i> = 175), the results showed that: on the one hand, leader workaholism enhanced subordinates’ intrinsic motivation which in turn promoted task performance; on the other hand, leader workaholism led to subordinates’ emotional exhaustion, which subsequently damaged task performance. Meanwhile, subordinates’ self-efficacy amplified the positive effect of leader workaholism on subordinates’ intrinsic motivation while mitigating the adverse impact on emotional exhaustion. This research contributes to the nascent body of literature by elucidating the dualistic effects and boundary conditions of leader workaholism on employee task performance, which provides managerial insights for leader-subordinate interactions.</p>