<p>This study empirically examines the impact of a growth mindset on secondary school students' academic engagement in mathematics, with particular emphasis on the sequential mediation effects of self-efficacy and achievement emotions. A survey of 1,583 secondary school students in Inner Mongolia, China, was conducted, and structural equation modelling was utilized for data analysis. The findings indicate that a growth mindset is positively correlated with students’ behavioural, emotional, and cognitive engagement in mathematics. Further mediation analysis showed that achievement emotions and self-efficacy significantly mediated the relationship between a growth mindset and the three dimensions of engagement. A growth mindset bolsters students’ engagement in mathematics by elevating their self-efficacy and fostering positive achievement emotions. This study offers valuable insights for educational practice, underscoring the critical importance of nurturing a growth mindset among adolescents and showcasing the pivotal role of emotions and self-efficacy in enhancing student engagement in mathematics. The results align with implicit and control-value theories, providing a novel perspective on the influence of a growth mindset on learning behaviours and laying a theoretical foundation for the development and implementation of targeted mathematics education interventions.</p>