Although recent years have seen a growing interest in students’ experiences of boredom in foreign language learning, scant attention has been paid to this negative emotion in online live classes. With a mixed-methods approach, this study investigated what factors were responsible for student boredom in online live classes and what made Chinese students majoring in English more bored in online live classes than in traditional in-person classes. Data were collected through a questionnaire and focus group interviews. Quantitative and qualitative data analyses revealed that the main factors responsible for this negative emotion in online live settings were teacher-centered classes, less engagement and interaction, high task challenges, monotonous and long learning activities, textbook-based activities, students’ lack of self-discipline, peer influences, the absence of emotional support, unreliable internet connection, physical fatigue, a locked-down campus, and a dormitory learning environment. Students’ greater boredom in online live settings than in-person settings arose from student-related factors, technological factors, and environment-related factors. This study sheds light on how to alleviate student boredom in foreign language learning in online live settings.