Using three-wave longitudinal data, this study tested the potential mediating roles of teacher-student relationship quality and teachers' career support efficacy in the association between Chinese adolescents' family socioeconomic status (SES) and career development (N = 1410). Results showed that adolescents' family SES at Wave 1 was negatively associated with their career ambivalence at Wave 3 via positive associations with both teacher-student relationship quality and teachers' career support efficacy at Wave 2. Moreover, adolescents' family SES at Wave 1 was positively related to career adaptability at Wave 3 via its positive association with teachers' career support efficacy at Wave 2. This study highlighted the important role of teacher-student interaction in adolescents' career development.