© The Author(s) 2022.Introduction: There is limited information on how the tendency to violence in adolescents is affected by internet addiction and insomnia. This study will contribute to the literature in revealing the effect of internet addiction on insomnia and violence tendency in adolescents. Methods: The data were collected between 26/May/2021 and 06/July/2021. A total of 2,502 adolescents studying in 9th and 12th grades were included in the study. Data were collected with the adolescent information form, Internet Addiction Scale-Short Form, Bergen Insomnia Scale, and Violence Tendency Scale. Descriptive statistics, independent samples t-test, one-way analysis of variance, correlation, and simple linear regression analyzes were used in the analysis of data. Results: Participants were 15.92 ± 1.19 years old and 70.80% were women. While internet addiction do not change according to gender, and violence tendency mean scores do not change according to having a device to use the internet, the study variable mean score changes according to all the other socio-demographic variables included in our study. There is a positive relationship between internet addiction, violence tendency, and insomnia. Furthermore, while internet addiction explained 22.1% of insomnia scores, 18.8% of the variance changes in the violence tendency scores, insomnia explained 11.8% of violence tendency scores. Conclusion: Although the scale scores of the adolescents in our study were below the average, internet addiction is common problem necessitates working on the subject. In our study, there is a significant relationship between internet addiction, insomnia and tendency to violence, and internet addiction predicts other variables.