Based on career construction theory, this study explored the relationship and mediating mechanisms between career adaptability and secondary school students' academic engagement. Four hundred and eight secondary school students from three Chinese secondary schools were surveyed using a three-wave time-lag design. The study found that career adaptability positively predicted academic engagement. Parental support and career hope mediated the relationship between career adaptability and academic engagement. Additionally, parental support and career hope also played a series of mediating roles between career adaptability and academic engagement. The results of this study contribute to the fields of positive psychology and occupational psychology research, extend the application of career construction theory to secondary students, and provide practical insights into increasing academic engagement and interventions for secondary students. The implications of these findings for practice and future research are discussed.