Background: Increasing rates of mental health problems among adolescents are of concern. Teens who are most in need of mental health attention are reluctant to seek help. A better understanding of the help-seeking in this population is needed to overcome this gap. Methods: Five databases were searched to identify the principal barriers, facilitators and interventions targeting help-seeking for common mental health problems in adolescents aged 10-19 years. The search was performed in June 2018 and updated in April 2019. Two independent screening processes were made using the eligibility criteria. Quality assessment of each study was performed, and findings summarised using a narrative synthesis. Results: Ninety studies meet the inclusion criteria for this review for barrier and facilitators (n = 54) and interventions (n = 36). Stigma and negative beliefs towards mental health services and professionals were the most cited barriers. Facilitators included previous positive experience with health services and mental health literacy. Most interventions were based on psychoeducation, which focused on general mental health knowledge, suicide and self-harm, stigma and depression. Other types of interventions included the use of multimedia and online tools, peer training and outreach initiatives. Overall, the quality of studies was low to medium and there was no general agreement regarding help-seeking definition and measurements. Conclusion: Most of the interventions took place in an educational setting however, it is important to consider adolescents outside the educational system. Encouraging help-seeking should come with the increased availability of mental health support for all adolescents in need, but this is still a major challenge for Child and Adolescent Mental Health Services. There is also a need to develop shared definitions, theoretical frameworks and higher methodological standards in research regarding help-seeking behaviours in adolescents. This will allow more consistency and generalisability of findings, improving the development of help-seeking interventions and ensuring timely access to mental health treatments.