Student engagement plays a crucial role in online courses. Despite its importance in online learning, student engagement can be influenced by a series of factors mainly coming from three aspects: instructors, learners, and objective conditions. This study aims to investigate the relationship between instructor factor (teaching presence), learner factor (self-regulation), objective condition factor (social interaction), and tertiary students' engagement of specific types (behavioral engagement, cognitive engagement, and emotional engagement) in the online courses using Tencent Meeting. Through linear regression analysis based on data collected by a questionnaire, the results show that self-regulation and social interaction are significantly related to engagement while teaching presence is not significantly related to engagement. Future research could improve engagement by applying virtual reality technology and focus on how to improve student engagement in online courses through various online course platforms and blended learning with the help of various online learning platforms.