Although engagement in the language learning process is important for students' language outcomes, factors that contribute to it are underexamined. Therefore, the aim of this study was to explore the roles of individual differences (growth language mindset and academic emotion) in shaping foreign language (FL) engagement. A total of 1,738 Chinese undergraduates (790 males and 948 females) studying English as a foreign language (EFL) completed questionnaires measuring their growth language mindsets, positive emotions (enjoyment, pride and hope), negative emotions (anger, anxiety, shame, hopelessness and boredom) and engagement during the English learning process. Correlational analyses revealed positive relationships between growth language mindsets, positive emotions, and engagement; and negative relationships between negative emotions and the three other variables. Structural equation modelling analyses showed that both positive and negative emotions were partial mediators between growth language mindset and engagement in FL learning, with positive emotions demonstrating larger effects. The findings are indicative of a motivation-emotion-behavior path in the EFL context. The theoretical and practical implications for language learning and teaching are discussed in this paper.