<p>Many studies have emphasized the impact of negative social experiences (such as shyness and loneliness) on depressive symptoms in adolescents. However, studies examining the interplay and underlying mechanisms among these three constructs from the perspective of social motivation remain relatively scarce. Against this backdrop, this study employed the Random Intercept Cross-Lagged Panel Model (RI-CLPM) to investigate the relationships among shyness, loneliness, and depressive symptoms from the perspective of two dominant types of social motivation development. Data were collected from 1214 Chinese adolescents (<i>M</i>_<i>age</i> = 15.46, <i>SD</i>_<i>age</i> = 0.71, 60.7% male) at three different time points, with each time point separated by six months. The results indicated that there are bidirectional relationships between shyness and the perceived social competence dimension of loneliness, and between the peer relationship evaluation dimension of loneliness and depressive symptoms. However, shyness only had a unidirectional predictive effect on depressive symptoms. The study also indicated that the marginally significant mediating role of the perceived social competence dimension of loneliness between shyness and depressive symptoms. Additionally, the research found no significant gender differences in shyness, loneliness, and depressive symptoms. These findings uncover the dynamic associations between shyness and the perceived social competence dimension of loneliness, and between the peer relationship evaluation dimension of loneliness and depressive symptoms, and emphasize the mediating role of the perceived social competence dimension of loneliness between shyness and depressive symptoms.</p>