Although the empathy–aggression relationship has been well documented, research has yet to establish whether emotions mediate and gender moderates this relationship in athletes, under conditions of low and high provocation. In this experiment, we assigned team-sport athletes to either a high (n = 40) or a low (n = 40) empathy group, and asked them to compete in a reaction-time task against a (fictitious) opponent, under conditions of low and high provocation. Empathy reduced aggression (i.e., intensity of electrical shock administered to the opponent) at low provocation in men, and at both low and high provocation in women. Guilt mediated the effect of empathy on aggression at low provocation in men; anger did not mediate any effects of empathy on aggression. Our findings indicate that the inhibitory effect of empathy on aggression and the mediating role of guilt are moderated by provocation and gender.