Introduction Adolescence and early adulthood is a time of many changes, such as changing schools, leaving home, starting college, or starting a new job. For many, these events, in addition to being exciting, can bring a lot of stress and anxiety. These feelings in some cases and if not recognized can lead to mental illnesses. The mental health of teenagers is essential because they are in a sensitive period that determines their personality and mental health. Satisfaction with life is among the things that play a significant role in the mental health of teenagers. For this reason, in this article, we are trying to examine the role of life satisfaction on the mental health of adolescents.Method: The descriptive research method is of correlation type. The selection of samples is done using a multi-stage sampling method, and 200 adolescent girls and boys (100 people in each group) will be selected as samples. The students filled out the TSLWS life satisfaction questionnaire. To analyze the research data, in addition to using statistical description methods, the Pearson correlation method is used to test the hypothesis. The data collection method is in the field. In this research, firstly, in the first stage, districts one and three were selected among the districts of the Karaj education region; in the second stage, ten schools were randomly selected from each district. Finally, in the third stage, students who were in the teenage age stage and were culturally, socially, and economically somewhat similar were identified and selected with the cooperation of school principals and teachers.Results: The results of the data analysis confirmed a positive and significant relationship between life satisfaction and mental health.