The growth mindset of socioeconomic status (SES growth mindset) refers to the belief that social standing is malleable and can be developed through one's efforts and practices. Individuals with a strong SES growth mindset tend to have a positive cognition of social class mobility, believing that they have the potential to reach a higher status. In line with implicit theory, the SES growth mindset has strong motivational functions, which may encourage individuals to acquire the resources necessary for improving their social standing. Given that higher education is pivotal for upward mobility, and college students are at a crucial stage in building their status, this research focused on how SES growth mindset influences their academic and career engagement. Drawing on resource scarcity theory, this research further incorporated how SES growth mindset interacts with family subjective SES to determine whether its impact varies among individuals with different SES backgrounds. To address these questions, we conducted two studies. Study 1 used a time-lagged method to investigate the relationships between SES growth mindset and the two types of engagement, as well as the moderating role of family subjective SES. Additionally, Study 1 examined whether time orientation mediated the moderation effect of family subjective SES. Study 2 aimed to test the causal effect of SES growth mindset on academic and career engagement with two scenario-based experiments. In Study 2a, we manipulated the SES growth mindset of participants and then tested their intentions to engage in academic and career tasks. In Study 2b, we further investigated how family subjective SES influences these relationships via time orientation. The results revealed that SES growth mindset has a positive impact on academic and career engagement. The relationship between SES growth mindset and academic engagement was stronger for individuals with a low family subjective SES, while the relationship between SES growth mindset and career engagement was stronger for individuals with high family subjective SES. Moreover, time orientation mediated the moderated effects of family subjective SES. Family subjective SES was positively associated with time orientation. Individuals with low family subjective SES held a near-future time orientation, which enhanced the effect of SES growth mindset on their academic engagement. By contrast, individuals with high family subjective SES have a far-future time orientation, causing the SES growth mindset to have a larger impact on their career engagement. In summary, this research highlights the importance of SES growth mindset in driving individuals' SES-promoted behaviors, which benefit their academic and career development. Such advantages are also influences by the family subjective SES and time orientation of individuals. Overall, the findings validate and expand the implications of implicit theory and resource scarcity theory, contributing to the understanding of class mobility from the perspective of personal initiative.