<p>Digital stress among adolescents is prevalent and likely fluctuates over time. However, existing research has paid limited attention to the developmental course of digital stress and its heterogeneity across individuals. This study investigated developmental trajectories of adolescent digital stress and further examined their digital-use predictors and mental health outcomes. A sample of 818 Chinese middle-school students (Wave 1: M_age = 12.75, SD = 0.75; 50.1% girls, 74.8% from rural areas) completed three survey waves over one year at 6-month intervals. Latent class growth modeling identified four trajectory classes of digital stress: <i>High Stress Holding</i> (8.9%), <i>Low Stress Rising</i> (17.7%), <i>High Stress Falling</i> (19.2%), and <i>Low Stress Holding</i> (54.2%). Social media use and digital social multitasking emerged as risk predictors of membership in adverse digital stress trajectories. <i>High Stress Holding</i> and <i>Low Stress Rising</i> classes were associated with depressive symptoms, whereas no significant associations were observed between any trajectory class and well-being. Findings highlight that considering heterogeneous developmental trajectories of digital stress is essential for understanding how digital-usage factors shape them and how they impact adolescent mental health.</p>