Adolescence and emerging adulthood are two life stages marked by notable cognitive and socioemotional changes. During both periods, friendships play an increasingly significant role and can significantly impact individuals positively or negatively. Despite the evolving nature of these relationships, parents remain crucial to the development of both adolescents and emerging adults, playing a key role in their well-being. This study aimed to investigate the mediating role of attachment to friends in the relationship between parental attachment and the well-being of Chilean adolescents and emerging adults. In a cross-sectional correlational study, 363 adolescents (48.2% female) aged 14 to 17 years (M = 15.33, SD = 0.95) and 199 emerging adults (67.8% female) aged 18 to 29 years (M = 22.42, SD = 2.53) completed the Inventory of Parent and Peer Attachment and the Pemberton Happiness Index Scale to assess general, eudaimonic, hedonic, and social well-being. Results of path analyses indicated that, for both adolescents and emerging adults, a more secure attachment to parents was directly associated with higher scores in all well-being dimensions. Additionally, more secure parental attachment was indirectly associated with better eudaimonic and social well-being through a more secure attachment to friends. These findings suggest that enhancing parental attachment could be a valuable focus in clinical interventions aimed at improving overall well-being in adolescents and emerging adults.