This study investigates how Korean EFL learners display self-efficacy and achievement emotions depending on their English competence. For this study, a total of 102 college students were classified into high-, intermediate-, and low-proficiency groups based on their proficiency levels. Four instruments were used in the study: a background questionnaire, a diagnostic assessment of English competency, the Questionnaire of English Self-Efficacy (QESE), and a short version of the Achievement Emotions Questionnaire (AEQ-S). The findings reveal that students in the high and intermediate groups had significantly greater outcomes than the learners in the low-level group in terms of English self-efficacy. In addition, the learners in the high and intermediate groups also demonstrated stronger positive achievement emotions while the low-level learners had stronger negative emotions. This study also proves that there were positive and negative correlations between self-efficacy, achievement emotions, and English competence. Based on the findings, pedagogical implications and suggestions are given for English instructors to help them better foster their learners’ affective growth.