Based on a scoping of the literature and consultations across the UN H6+ Technical Working Group, youth networks, and adolescent-serving organizations, we propose a short and an expanded definition of adolescent well-being. We also propose five interconnected domains for adolescent well-being and the requirements for adolescents to achieve well-being within each of these domains. The five domains encompass both subjective and objective constructs and include health as one of the five domains. The domains are also underpinned by gender, equity, and rights considerations. An individual’s degree of independence to access opportunities that foster their own well-being will vary across the decade of adolescence. Although important at all ages, adolescent well-being may, therefore, require greater adult support at younger ages. The examples that are given in the subdomains and the requirements to achieve these are illustrative and not exhaustive.