IntroductionThe Resourceful Adolescent Program (RAP) is an evidence-based resilience intervention for adolescents. Operating in a strength-focused paradigm, the programme uses an integration of cognitive behavioural therapy and interpersonal psychotherapy to improve coping skills and build resilience. This study aims to establish whether a culturally and linguistically adapted intervention informed by RAP principles is effective in increasing resilience, enhancing coping skills and preventing symptoms of depression and anxiety.Methods and analysisWe will translate, back-translate and culturally adapt the RAP for adolescents and training materials for facilitators, and the adapted intervention will be called Happy House. A two-arm parallel controlled trial will be conducted in eight high schools in the north of Vietnam. In each of the selected schools, all students from four randomly selected grade 10 classes (an estimation of about 1204 students) will be invited to participate. The control group will receive the usual curriculum. The intervention group will receive six weekly 90 min school-based group sessions of Happy House in addition to the usual curriculum. The primary outcome, depressive symptoms, will be measured using a locally validated version of the Centre for Epidemiologic Studies Depression Scale Revised. Secondary outcomes are mental well-being, coping self-efficacy, school connectedness, anger management and health risk behaviours. Data will be collected at recruitment, and at two weeks and six months post intervention. Mixed-effect logistic regression for the main outcome and mixed-effect linear and logistic regression models for the secondary outcomes will be conducted to estimate the effects of the intervention on the outcomes.Ethics and disseminationThis trial has been approved by Monash University Human Research Ethics Committee (No. 21455) and the Institutional Review Board of the Hanoi School of Public Health (488/2019/YTCC-HD3). Dissemination of findings will include peer-reviewed publications, international and national conferences, seminar and media presentations, national policy briefings in Vietnam, local language reports and lay language summaries for participants.Trial registration numbersRegistered with the Australian New Zealand Clinical Trials Registry, registration number: ACTRN12620000088943 (3/2/2020).WHO Universal Trial Number: U1111-1246-4079.