Adolescents, particularly today’s Generation Alpha, face uncertainty about whether, when and how their autonomy will be respected, especially in mental health contexts. Existing consent and confidentiality practices may not reflect adolescents’ preferences, potentially deterring help-seeking. This Feature examines the tension between adolescent autonomy and parental authority in mental healthcare. We synthesise interdisciplinary perspectives from the developmental sciences, medical ethics and law. We present data from 20 844 students (aged 11–18 years) in the 2023 OxWell Student Survey regarding barriers to accessing mental health support. Among those who wanted but had not accessed additional support (n = 2792), 72.3% reported privacy/confidentiality concerns, with half (50.3%) specifically citing that they did not want their parents to know. These concerns were particularly common among students reporting self-harm, gender-diverse adolescents and those in less stable home environments. We argue that respecting adolescent autonomy must be central to healthcare planning, not only as an ethical and legal imperative, but also to enable timely support. A capacity-based, adolescent-centred approach – grounded in greater transparency, clearer explanations of when and how information may be shared (including the option to involve a trusted adult) and consistent, aligned policies across institutions, especially around parental involvement, could help address a key barrier to care.