With the advancement of digital technology, online learning is no longer merely a potential learning method to enable a diverse range of learners’ access to education, but is increasingly becoming a crucial learning method at every school level. The majority of research problems and challenges regarding online learning stems from the question of how learners obtain and maintain positive learning motivation in online learning settings. This study seeks to examine the situational motivation of high school students enrolled in continuing education programs via online learning in Vietnam, thereby examining the differences by genders, groups, online learning duration, and online learning programs. The snowball sampling method was utilized, and the questionnaire was designed using the Google Forms tool. The data set for analysis includes 633 records collected between September 17 and October 10, 2021. The study’s findings investigated the situational motivation of continuing education learners in online learning in Vietnam, in which: Situational Motivation Scales varied in factors of Intrinsic Motivation, Identified Regulation, External Regulation, and Amotivation. In addition, the research findings indicate disparities of situational motivation in online learning between male and female learners, by school grades, by learning time, and by learning program. Firstly, the results reveal that there is a difference by gender and duration of online learning between three factors of Intrinsic Motivation, Identified Regulation, External Regulation, and Amotivation. Secondly, the results by school grades show differences in factors within the same grades as well as disparities across grades in the same factor. Third, the findings for SMS of learners enrolled in an online learning program suggest that there is a difference by subject in the same factor and a difference in a subject with various factors. Therefore, these findings are expected to provide critical evidence for academics studying learner motivation in general, and online learners in particular. Furthermore, the findings can help educators and teachers better understand the situational motivation of continuing education learners in the online learning environment, in order to have effective pedagogical and psychological measures in place to encourage effective online learning, increase the quality of online teaching and learning, and move learners toward self-determination.