<p>This study examines the mediating role of psychological flexibility and vulnerability variables in the relationships between multiple-screen addiction and depression, anxiety, and stress. Data were collected from 309 high school students (M age = 16.13, SD = 1.40; 57% girls, 43% boys). Analyses were conducted using SPSS 25 and Hayes Model 4. Data were collected using the Multi-Screen Addiction Scale (MSA), the Depression, Anxiety, and Stress Scale (DASS-21), the Psychological Vulnerability Scale, and the Acceptance and Action Questionnaire-II (AAQ-II). Findings show that students with MSA and high levels of depression, anxiety, and stress have low levels of psychological flexibility and high levels of psychological vulnerability. More importantly, psychological flexibility and vulnerability were found to play a fully mediating role in this relationship. As a result, it seems that strengthening psychological flexibility and reducing vulnerability have a significant effect in reducing the adverse effects of depression, anxiety, and stress caused by MSA in students. These findings can provide necessary guidance in developing intervention programs and school policies.</p>