Background: Self-Help Internet Cognitive Behavioural Therapy (iCBT) interventions are highly efficacious and overcome numerous barriers adolescents experience when accessing face-to-face interventions, including stigma, privacy, lengthy wait lists and cost. Despite this, adolescents struggle to engage in Self-Help iCBT, which is problematic given that there is a relationship between higher engagement and better treatment outcomes. The reasons for poor engagement among adolescents are unclear. Using the iCBT program, BRAVE Self-Help as an example, this study explored 1) the barriers to engagement directly from the adolescent’s perspective and, 2) their viewpoints on enhancing engagement in iCBT. Method: Semi-structured interviews were conducted with 14 adolescents aged 12-17 years ( M = 14.36, SD = 2.12) who had participated in BRAVE Self-Help in the previous 12 months. Reflexive thematic analysis was utilised to analyse data. Results: Stigma, program factors (program design, content and length) and environmental factors (competing priorities and distractions), were identified as adolescent barriers to engagement. With respect to strategies to enhance engagement, adolescents identified 1) specific program factors (positive reinforcement and personalisation), and 2) support factors (reminders and optional support). Conclusions: Co-design methods with adolescents at both the design and implementation stages of iCBT programs is imperative for engagement.