Different types of specific anxiety symptoms commonly co-occur but also display distinct developmental trajectories over time in children and adolescents. Nevertheless, little is known about the co-developmental trajectories of specific anxiety symptoms among youth during the transition into adolescence and how identified trajectories are associated with important psychological and academic outcomes. This study thus aimed to determine the (a) heterogeneous co-developmental trajectories of five specific anxiety symptoms (generalized anxiety, separation anxiety, social anxiety, school anxiety, and panic disorder) from middle childhood to early adolescence, and (b) associations between the identified, distinct trajectories and youth’s psychological well-being and academic achievement. A total of 715 Chinese elementary school students (45.6% girls, Mage = 8.96, SD = 0.76) completed measures on six occasions across three years, using 6-month intervals. Parallel process latent class growth modeling revealed five distinct anxiety trajectory groups: “congruent-low” (49.8%), “moderately low with predominant social anxiety” (18.5%), “moderately low with predominant school anxiety” (12.6%), “moderately high with predominant generalized and social anxiety” (8.6%), and “congruent-high” (10.5%). The lowest psychological well-being and academic achievement were observed for youth who persistently experienced the co-occurrence of two or more specific anxiety symptoms, followed by those who persistently experienced one predominant anxiety symptom, and finally, youth who persistently experienced low levels of all five specific anxiety symptoms. The identification of five heterogeneous groups with differential outcomes highlights the importance of individual differences considerations in understanding the co-developmental patterns of specific anxiety symptoms from middle childhood to early adolescence and the need for more sophisticated intervention programs tailored to members of specific groups to promote optimal psychological well-being and academic success.