This study examined the impact of the AI-based Immersive Reader on Korean high school students’ English reading comprehension and their perceptions. Over eight weeks, the experimental group (n = 21) used Immersive Reader to read L2 texts, while the control group (n = 19) participated in traditional reading instruction. Data from preand post-tests, as well as surveys, were analyzed quantitatively. The findings reveal several key points: First, the experimental group demonstrated a statistically significant improvement in reading comprehension. Second, this enhancement was particularly evident among intermediate-proficiency students, who showed the most substantial gains. Third, survey results indicated that using Immersive Reader led to more positive attitudes toward English learning and reading, boosting students’ interest, confidence, and motivation while decreasing anxiety. Overall, these results suggest that Immersive Reader is an effective AI-based tool for enhancing both cognitive and affective aspects of L2 learning. The study underscores the potential of incorporating Immersive Reader into English education to foster self-directed learning.