Meaningful musical experiences during youth can leave a lasting impression on an individual by shaping their identity and place in the world. This study examines such experiences in relation to autobiography and self-identity. An online questionnaire ( N = 50) was distributed to establish how individuals understood musical experiences from their youth as important to their past and present self-identities. Following the online study, 10 questionnaire participants were selected to be interviewed to further examine the meanings created within their nominated experiences, and how these meanings had been autobiographically contextualised against the backdrop of the memory of these experiences. Questionnaire data was analysed using Thematic Analysis to establish shared autobiographical- and identity-related concepts. Interpretative Phenomenological Analysis served as the methodological framework for analysing the participant interviews to support a more individualised interpretation of each participant’s experience. Data from the online questionnaire were analysed to reveal a network of identity- and autobiography-relevant themes, which were organised under three wider thematic categories: the self, the social, and the musical. Analysis of the interviews, guided by Identity Theory, revealed individual differences in participants’ processes of identity formation, relationships with music, and attitudes towards their past selves. In both sets of data, prominent themes emerged around ideas of personal transformation and pivoting to a new path in life. These findings frame autobiographically significant musical experiences as powerful in their potential to contribute to identity formation, although their impact varies for each individual. We assessed this autobiographical significance through the enduring salience over time of the identity the experience affected, enabled by our respondents’ reflections on both their past and their present self-identities. Our results illustrate that music can support a wide range of self-identity-relevant meanings, and fundamentally transform our sense of who we are.