Short-term and structured cognitive behavioral problem-solving therapy (PST) is a developmentally relevant mode of action for the treatment of emotional problems in young people. This study aimed at testing the efficacy of a problem-solving therapy in treating depression and suicide potential in adolescents and young adults. A total of 46 self-referred high school and university students who were randomly assigned to a problem-solving therapy (n = 27) and a waiting list control (n = 19) conditions completed a controlled cognitive behavioral problem-solving treatment trial. Participants were administered the measures of depression, suicide potential, problem solving, self-esteem and assertiveness. Twenty-two of the 27 participants from the PST condition could be reached after 12-months for follow-up. Participants completed depression and problem-solving measures at follow-up. Results showed that post-treatment depression and suicide risk scores of participants within the PST condition decreased significantly compared to the pre-treatment scores but post-waiting and pre-waiting depression and suicide risk scores of participants within the WLC condition were unchanged. Likewise, post-treatment self-esteem and assertiveness scores of participants within the PST condition increased significantly compared to the pre-treatment scores while post-waiting and pre-waiting self-esteem and assertiveness scores of participants within the WLC condition were unchanged. At post-treatment, 77.8% of the participants in the PST but only 15.8% of those in the WLC condition achieved full or partial recovery according to BDI scores. Similarly, 96.3% of participants in the PST but only 21.1% of those in the WLC condition achieved full or partial recovery according to HDRS scores. The improvements were maintained at 12-months follow-up. Therefore, it is concluded that problem-solving therapy should be considered as a viable option for the treatment of depression and suicide potential in adolescents and young adults.