Abstract Background Like many low- and middle-income countries, almost half of the proportion of the South African population is under the age of 25. Given the peak age of onset for most mental health problems is in adolescence, it is vital that adolescents have access to mental health counselling. There are several initiatives to increase access to mental health counselling in South Africa, primarily through the integration of counselling for common mental disorders (CMD) into primary health care services, but adolescents (15–18 years of age) generally do not utilize these services. To address this gap, we will undertake a study to explore the feasibility of conducting a trial of the effectiveness of a community-based mental health counselling intervention for adolescents at-risk for a CMD. Methods The study is a feasibility trial of the ASPIRE intervention, a four-session blended multi-component counselling intervention adapted for South African adolescents at risk for depression and alcohol use disorders. We will enrol 100 adolescents from community settings and randomly assign them to the ASPIRE intervention or a comparison condition. Feasibility measures, such as rates of recruitment, consent to participate in the trial and retention, will be calculated. Qualitative interviews with participants and counsellors will explore the acceptability of the intervention. The primary outcomes for a subsequent trial would be reductions in symptoms of depression and days of heavy drinking which will be measured at baseline, 6 weeks, and 3 months post-randomization. Discussion This feasibility trial using a mixed-methods design will allow us to determine whether we can move forward to a larger effectiveness trial of the ASPIRE intervention. Trial registration The trial is registered with the Pan African Clinical Trials Registry (PACTR20200352214510). Registered 28 February 2020—retrospectively registered, https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=9795