This study was conducted to investigate the role of Internet addiction on depression in female high school students in Ardabil. This study is an applied research in terms of its purpose. In terms of data collection method, the present research method is descriptive. Descriptive-correlational research was used to determine the relationship between variables. The statistical population included all female high school students in Ardabil in the academic year 1402-1403. According to the statistics provided by the Ardabil Education Department, 1865 people were studying in this city. The sampling method in this study was stratified random sampling. Considering the size of the statistical population, the sample size was determined to be 319 people based on the Cochran formula. The measurement tools of this study were the Kimberly Young Internet Addiction Test (1998), the Beck Depression Inventory - Second Edition (BDI-II (1961). For descriptive statistics, frequency, percentage, mean, standard deviation, and variance indices were used to analyze the data, and for inferential statistics, the Kolmogorov-Smirnov test and Pearson correlation coefficient were used to examine the distribution of data. Multiple linear regression and SPSS 27 software were used to examine the effect of Internet addiction on dependent variables. According to the results of the analysis of the fit indices of the research model, since the values ​​of Cronbach's alpha, rho_a, and CR in all variables were greater than 0.7 and the AVE value was greater than 0.5, the reliability and validity of the data were confirmed. The results of the study showed that, considering the correlation coefficients obtained for the relationship between Internet addiction and anxiety (0.355) and depression (0.555), it can be concluded that there is a direct relationship between Internet addiction and depression.