AbstractLearning academic disciplinary knowledge through English as a medium of instruction (EMI) in higher education can be emotionally taxing. However, compared to the bulk of studies investigating the role of emotions in language learning, research that explores students’ emotional experiences in EMI contexts remains scarce. Drawing on a sample of 746 undergraduate students at an EMI university in China, the present study disentangles how two heavily researched emotions (i.e., enjoyment and anxiety) affect students’ learning motivation and willingness to communicate (WTC) inside and outside of EMI classrooms. Students’ motivation is conceptualized through the notion of ideal self to represent their aspired future self‐image as competent language users (ideal L2 self) and subject experts in the field (ideal disciplinary self). Results from structural equation modeling analyses highlighted enjoyment as a strong positive predictor for both ideal selves and WTC. In contrast, anxiety failed to predict neither ideal L2 self nor ideal disciplinary self but had a negative effect on WTC. The two types of ideal selves were found to differ in their respective impact on students’ WTC inside of EMI classrooms yet neither predicted WTC outside of classrooms. Pedagogical implications for EMI teaching and learning are provided.