The study explored the learning engagement of BYOD (Bring your own device) in a blended-learning classroom. In a blended learning environment, 51 undergraduates of the same class participated in two core courses. In Course A, as the experimental group, they brought their own devices to facilitate their learning, whereas in Course B, as the control group, they did not. The study compared the undergraduates' engagement in the two courses. The results of the learning behavior analysis on the learning platform system and interviews after the 16-week courses showed that BYOD in the classroom improved the undergraduates' engagement in the blended learning classroom. Finally, the study is suggested that instructors and researchers could design learning activities in the classroom with BYOD support to improve undergraduates' engagement.Index Terms-Blended learning, undergraduate, bring your own device (BYOD), learning engagement.