This study investigates the moderating role of emotional intelligence (EI) in the spillover of task conflict into relationship conflict in subordinate-supervisor relationships. Grounded in the ability-based EI model, the research focuses on the emotion management ability of subordinates. Data were collected from 113 employees through an online survey, followed by hierarchical regression analysis. Findings revealed a significant negative relationship between EI and relationship conflict. Additionally, a significant positive link was observed between task conflict and relationship conflict. Emotional intelligence significantly moderates this relationship, with higher EI attenuating the spillover effect of task conflict on relationship conflict. In summary, employees with higher EI effectively manage interpersonal conflicts with their supervisors, fostering constructive interactions. Furthermore, subordinates’ EI acts as a buffering moderator, preventing task conflict from transforming into relationship conflict. This research offers practical implications and suggests avenues for future inquiry.