Abstract Background Colombia has one of the largest populations of internally displaced individuals by an armed conflict. However, there is no data demonstrating its effect on health, particularly in adolescents. Purpose To describe the prevalence and associations of mental illness in the adolescent population displaced by violence in Colombia. Methods We conducted a secondary analysis of the 2015 National Mental Health Survey (NMHS), which provides data of mental health issues (SRQ), mental health disorders (CIDI-CAPI) and sociodemographic characteristics. Results Of the 1754 adolescents interviewed 5.3% (95% CI 4.1 to 6.9) mentioned a change in residence due to violence. Among them 38.5% lived in poverty compared to 23.6% of those non-displaced by the conflict. Suicidal thoughts and suicide attempt were present in 19.8% and 9.1% of displaced adolescents respectively, compared to 5.8% and 2.1% of non-displaced adolescents. The prevalence of post-traumatic stress disorder (PTSD) and any mental health disorder (measured with the CIDI-CAPI) was higher in the displaced population 12.3%, 11% respectively, in contrast to 2.1% and 7% of those non-displaced. Finally, anxiety and depressive disorders were more common among displaced adolescents. Conclusion A higher prevalence of mental health conditions and disorders is observed among displaced adolescents.