The present study aimed to develop a structural equation model of internet addiction based on Machiavellianism and anxious attachment style, with a focus on the mediating role of psychological loneliness among female high school students. This research employed a descriptive-correlational design. Participants were selected through a multistage cluster random sampling method, and data were collected using standardized questionnaires assessing internet addiction, dark triad personality traits, adult attachment styles, and psychological loneliness. Data analysis was conducted using structural equation modeling (SEM). The findings indicated that Machiavellianism, anxious attachment, and psychological loneliness had significant direct effects on internet addiction. Additionally, Machiavellianism and anxious attachment were significant predictors of psychological loneliness. The mediating role of psychological loneliness in the relationship between Machiavellianism and anxious attachment with internet addiction was also confirmed. These results suggest that personality and emotional variables—particularly Machiavellianism, anxious attachment, and psychological loneliness—play a critical role in the development and persistence of internet addiction among adolescents. The findings provide practical implications for the design of preventive and psychological intervention programs aimed at enhancing students’ mental health.
