According to career construction theory, middle school students are in a critical phase of growth and exploration that requires self-reflection on their interests, values, and aspirations. Career adaptability is a key indicator of career development for middle school students and a crucial ability for achieving career success. Research indicates that many Chinese middle school students face significant hurdles in their career development, including a lack of motivation, limited self-awareness, and unclear career trajectories. To address these challenges, it is imperative to explore the factors influencing career adaptability, with a particular focus on the role of parental and teacher autonomy support within the framework of self-determination theory. This study aims to explore the correlation between parental autonomy support (PAS), teacher autonomy support (TAS), core self-evaluations (CSE), and career adaptability (CA) among middle school students. The longitudinal data for this study were collected from two middle schools in the Anhui province. Middle school students were recruited as research participants through a cluster sampling method. A total of 482 students were surveyed in three stages during a 1-year period, and a cross-lag model was employed to analyze the data. (1) From T1 to T2, T1PAS predicted T2CS, T1CSE predicted T2CA, and T1CA predicted T2TA; (2) from T2 to T3, T2PAS predicted T3CS, T2CSE predicted T3CA, and T2TAS predicted T3PAS; (3) TAS did not predict CSE and CA over time; (4) T2CSE mediated the relationship between T1PAS and T3CA. These findings suggest that autonomy support has a consistently positive influence on the career development of early adolescents. Valuing children's autonomy is beneficial for fostering positive self-evaluations and shaping their career trajectories. Autonomy support plays a pivotal role in enhancing middle school students' career adaptability and promoting career development by strengthening self-evaluations. Additionally, the effect of parental autonomy support is more stable than that of teacher autonomy support.