Socioeconomic status (SES) is one of the well-recognized determinants of individual academic achievement. Past studies have mostly focused on the effect of SES ranking but not on that of perceptions of the changeability of SES (mindset of SES). The current study addressed this gap by investigating the association between mindset of SES and academic achievement among adolescents. We also tested the roles of hopefulness and school engagement in explaining this association. Questionnaires were administered to 686 middle school students. Measures for mindset of SES, hopefulness, school engagement, and academic achievement were collected along with a set of sociodemographic variables. The results showed that growth mindset of SES was associated with higher academic achievement. An indirect pathway was found for this association through higher levels of hopefulness and school engagement. The findings highlight the importance of mindset of SES in shaping the academic achievement of adolescents. Future educational intervention programs might focus on growth mindset of SES, hopefulness, and school engagement to enhance adolescents' academic achievement.