Attachment theories postulate that during adolescence, peer relationships become more important as a predictor of positive social, emotional and behavioral outcomes. Adolescents develop the ability to empathize with others, which is related to healthy functioning and positive peer relationships. Empathy has been studied as a potential mechanism that may help to explain how strong and healthy emotional bonds are associated with less emotional disorders and conduct problems in youth. The main purpose of this study was to examine the relationship between peer attachment and strengths and difficulties during adolescence, considering empathy as a potential mediator of this association. A total of 800 Spanish adolescents (56.65% girls), aged between 12 and 15 years (M = 14.02, SD = 1.21), completed measures of peer attachment, empathy, conduct problems, emotional difficulties and prosocial behavior. Structural equation models indicated that peer attachment was negatively associated with conduct problems and emotional difficulties but positively related to prosocial behavior. In general, empathy mediated the link between peer attachment and both emotional and behavioral outcomes, without significant group differences between boys and girls. The discussion focuses on the importance of healthy peer relationships as a powerful predictor of emotional well-being and psychological problems in adolescence.