The study aims to explore the impact of applying online-based role-playing activities on elementary English language learners’ reading and writing skills as well as their perceptions and attitudes. Both qualitative and qualitative data were collected through data triangulation for eight weeks with 49 fifth graders from an elementary school in Korea. The results suggest a significant impact on both the reading and writing skills of all learners, with some variation across learner levels: the middle and low-level groups showed a more noticeable improvement than the high-level group. It is also noted that the process of drafting role-play scripts by themselves, revising and improving them through feedback activities, and reflecting on them through keeping a growth journal are believed to have enhanced learner autonomy. These all may provide insights into facilitating successful online-based language learning tools in Korean elementary English classes.