This study aims to create and validate an assessment tool for gauging language learners’ perceptions of teacher support and understanding how such perceptions correlate with English proficiency among Korean EFL college students. The research consists of two experimental phases. In the first experiment, 321 participants were recruited to identify key factors related to teacher support in English language classrooms. In the second experiment, 102 participants were assessed to explore the link between their perceptions of teacher support and their English competency. The results reveal that the scale created for this study, the English Language Learners’ Perceived Teacher Support (ELLPTS) instrument, encompasses five major subcategories: positive emotional support, informative academic support, cooperative condition support, cultural knowledge support, and supplementary resource support. The results also indicate that learners in the high- and medium-achieving groups exhibited more positive outcomes in cooperative condition, cultural knowledge, and supplementary resource support compared to low-proficiency learners. Pedagogical implications and practical teaching methods for L2 learning settings are discussed.