This study examines how and when passionate leaders can instigate work passion in their followers. We propose relational energy as a social interaction mediator that can facilitate the crossover of work passion from leader to followers. Additionally, we introduce a moderator of culture (Anglo culture, e.g., Canada vs. Confucian Asian culture, e.g., China) as it plays a vital role in the dynamics of interpersonal relations within a leader-follower dyad. We collected two-wave data from MBA students of two Confucian Asian countries (China and Singapore, n = 120) and two Anglo countries (Canada and Australia, n = 265) to test our moderated mediation model. The results show that interactions with passionate leaders can generate relational energy in followers and subsequently lead to followers’ passion for work. Furthermore, the findings shed light on the moderating effect of culture, such that the leader-follower work passion relationship via follower relational energy was stronger for followers from Anglo culture than the followers from Confucian Asian culture. Limitations of the study and directions for future research are discussed.