This study explores learners’ perceptions and readiness before and after online English courses, focusing on Korean EFL college students. One-hundred and eighty-four first-year college students were assigned to high-, intermediate-, or low-proficiency groups. A background questionnaire, the Online English Learning Perceptions (OELP) scale, the Online English Learning Readiness (OELR) scale, and a diagnostic assessment of English competence were utilized in this study. The results indicate that the students’ proficiency levels played a large role in determining their perceptions and their readiness towards online courses. High- and intermediate-proficiency learners showed greater outcomes than lower-proficiency learners in terms of adaptability, knowledge acquisition, and ease of loading in the OELP as well as their own self-directed learning, learner control, and motivation for learning, which were measured using the OELR. This study also reveals that all groups displayed significant improvement in terms of English competence after engaging in online courses. Based on the findings, the current study suggests pedagogical implications and possible instructional strategies teachers can use in online language classrooms.