摘要:This study aimed to identify smartphone overdependency and stress’ combined effects on depression and suicide-related behaviors, such as suicidal ideation, plans, and attempts, among Korean high school students. Cross-sectional secondary data analysis was conducted using data from the 2020 Korea Youth Risk Behavior Web-based Survey. This study included 25,987 high school students. Data were analyzed using descriptive analysis, Rao-Scott chi-square test, and logistic regression based on a complex sample design. Regardless of smartphone overdependence, some stress and high stress were associated with higher depression than no stress and no smartphone overdependence. Furthermore, regardless of smartphone overdependence, some stress and high stress were associated with greater depression and suicidal ideation than no stress and no smartphone overdependence. However, only high stress was associated with suicide plans and attempts. Additionally, stress with smartphone overdependence increased the risk of depression and suicide-related behaviors, whereas the absence of stress did not significantly affect depression and suicide-related behaviors. Therefore, to prevent depression and suicide-related behaviors among high school students, continuous monitoring of and interventions to reduce stress levels should be prioritized. Moreover, as stress combined with smartphone overdependence increases the likelihood of depression and suicide-related behaviors, educational programs to prevent smartphone overdependence should be developed.