Aim <p>The aim of the study is to evaluate the effects of a nursing intervention program on appropriate internet use, loneliness, and family harmony in adolescents who are problematic internet users.</p> Methods <p>The first phase of this study, which was conducted with a sample of 490 people in a population of 1010 people, was a descriptive study, and the second phase was a randomized controlled experimental study. The second phase of the study was conducted with 74 adolescents who were divided into control and intervention groups among 93 adolescents identified as problematic internet addicts.</p> Results <p>The rate of adolescents with problematic internet use was determined to be 18.98%. When the mean scores obtained from the scales applied in the study were compared, it was determined that the difference between the pre-test and post-test mean scores of the adolescents in the intervention group was statistically significant.</p> Conclusion <p>In the light of these results, it was shown that the nursing intervention program applied in the study positively affected family harmony and reduced internet addiction and loneliness in adolescents with problematic internet use.</p>