Flipped learning has received growing attention as an important instructional approach leading to students' learning performance and higher order thinking abilities. This study applied flipped learning to a large university class to improve its major weakness, students' low engagement, and investigated the effects of self-regulation and transactional distance on learning engagement. The participants of this study were 390 undergraduate students who were enrolled in a general education course "Philosophy of Consideration" at a large university in South Korea. Analyses of an online survey completed in the Fall semester of 2018 indicate that self-regulation affected learning engagement and transactional interaction. Transactional interaction also affected learning engagement. In addition, transactional distance was found to mediate the relationship between self-regulation and learning engagement. That is, self-regulation affected learning engagement both directly and indirectly. However, students' past flipped learning experience did not moderate the relationships among self-regulation, transactional interaction, and learning engagement. The research findings of this study confirmed the importance of self-regulation and transactional distance for improving learning engagement in a large university class. Finally, this study directly addresses prevailing concerns about how to effectively teach a large university class.