ABSTRACT Amid the increasing research on language learner agency, attention has rarely been paid to the psychological process of agency construction. Specifically, the role that emotions play in this process requires further investigation due to the emotion‐laden nature of foreign language learning. Drawing on Bandura's (1989) social cognitive theory, this study examined the interplay between agency and emotions in the English learning experiences of secondary school EFL learners who achieved high levels of English proficiency. The data were collected from 10 secondary school students in China through written Critical Incident Technique reports and semi‐structured interviews. All the data were analyzed in NVivo using both deductive and inductive approaches. Results showed that learner emotions were both resources for and results of agency. Positive emotions and the process of overcoming negative emotions nurtured the learners’ sense of agency, while a high level of agency generated more positive feelings and mitigated the negative emotions’ impact on learning motivation and engagement. Practical implications for language teachers and parents are discussed.