This study analyzes how Korean college students’ mindsets toward language learning affect their English language performance and also explores the relation between the two variables. A total of 236 participants were categorized into three groups based on their proficiency levels, advanced, intermediate, and low. Three instruments were used in the study: a background questionnaire, the Language Mindsets Inventory (LMI), and an English competency test. The results indicate that the advanced and intermediate groups were significantly more likely to exhibit a growth mindset, a term that relates believing one can improve, compared to the low-level group. Conversely, the low-level group demonstrated a significant proclivity toward a fixed mindset, a belief that one cannot improve. The study also reveals a positive correlation between the growth mindset and language performance, while the fixed mindset was negatively associated with learning outcomes. Based on the findings, the present study recommends a more nurturing pedagogical approach to facilitate language learners’ mindsets in L2 classes, specific examples of which are outlined.