Objective: ADHD is often a lifelong condition, and has grown increasingly prevalent over the past few decades. Adolescence is a period characterized by the quest to develop a coherent identity, yet relatively little research has examined the relationship between ADHD diagnosis and identity. The purpose of this study was to explore the importance of experiences of the healthcare system and of peer relationships in the identity formation of adolescents with ADHD. Method: This was investigated through semi-structured interviews with 10 adolescents (n = 8 females and 2 males) aged 15 to 18 years. An inductive thematic analysis was conducted within a narrative framework. Results: The results revealed seven main themes indicating that ADHD played a central role in the adolescents' self-narratives: (1) limited effect of Child and Adolescent Psychiatry (CAP) contact on identity formation, (2) the ADHD concept as meaning-making, (3) heterogeneity of the role of medication on identity formation, (4) negotiation of identity in relation to others, (5) varying degrees of acceptance in different relationships, (6) perceiving oneself as a troublemaker, and (7) relationship difficulties. Conclusions: Overall, the diagnosis constituted an important narrative and "symptoms" of ADHD rather than the "label" of ADHD tended to be stigmatizing. Furthermore, medication affected identity, and some felt pressured to medicate to adhere to social norms. A common pattern was that adolescents set aside their individual identity in favor of their relational identity.