The formation of friendships and romantic relationships represents an important developmental task in young adulthood. However, little is known about the potential factors associated with the quality of these interpersonal relationships. This cross-sectional study aimed to examine whether attachment representations to parents and depressive symptoms were independently associated with the quality of friendships and romantic relationships. Using the Prolific platform, 196 young adults (M age = 22.01 years, SD = 1.62) participated in the study. Each participant reported their attachment representations to mother and father and depressive symptoms through the Inventory of Parent and Peer Attachment and Patient Health Questionnaire 8, respectively. Positive (companionship, intimate disclosure, emotional support, approval, and satisfaction) and negative (conflict, criticism, pressure, exclusion, and dominance) dimensions of relationship quality with a close friend and a romantic partner were assessed with the Network of Relationships Inventory-Relationship Quality Version. Results showed that secure attachment representations to mother (but not father) were significantly associated with increased emotional support, approval, and satisfaction in romantic relationships, even after controlling for gender and depressive symptoms. Increased depressive symptoms were significantly associated with more conflict, criticism, and pressure in friendships, above and beyond gender and attachment representations to parents. There was a significant interaction between gender and depressive symptoms in predicting friendship quality. Men with increased depressive symptoms reported more conflict and dominance. No significant effects were found for women. These findings underscore the importance of secure attachment representations to mother in predicting healthy romantic relationships and depressive symptoms in predicting problematic friendships, especially for men.