This study explores how Korean EFL learners with different proficiency levels exhibited emotion regulation strategies and engagement in language classrooms. A total of 171 college students were recruited and divided into high-, intermediate-, and low-proficiency groups. This study utilized four instruments: a background questionnaire, a test of English competency, the Academic Emotion Regulation Questionnaire (AERQ), and the Foreign Language Classroom Engagement Scale (FLCES). The findings reveal that learners in the high-proficiency group had greater outcomes than low-level learners on the developing competences while low-level learners had significantly higher outcomes than those who were high-level on the reappraisal and venting in the AERQ. This study also indicates that learners in the high and intermediate groups had significantly greater outcomes than those with lower proficiency level on the factors of the FLCES, meaning that the former two groups were more engaged during class. Comparing emotion regulation and engagement, positive and negative correlations were found between those two variables and the students’ overall language competence. Pedagogical implications for encouraging language learners to better regulate their emotions and engage during class are offered in the study.