Our study leverages insights from the conservation of resources theory and job demands–resources theory to explore the relationship between two types of emotional labor—surface acting and deep acting—and job performance among firefighters. Furthermore, we assess the moderating roles of transactional and transformational leadership within this framework. Using hierarchical multiple regression models, we analyzed data from 1453 firefighters in Gyeonggi-do, South Korea’s most populous province. The findings reveal that surface acting adversely affects job performance, whereas deep acting exerts no significant impact. The relationships between these two types of emotional labor are contingent on transactional and transformational leadership. The policy implications of this study include the need to manage employees’ emotional labor by distinguishing between surface and deep acting as well as the need for efforts and alternatives to facilitate transactional and transformational leadership.