Objectives This study aimed to assess self‐reported social media use, professional behaviors online, and perceptions on e‐professionalism while using social media among dental students in two Southeast Asian universities. Methods This cross‐sectional study involved clinical dental students at University of Malaya (UM), Malaysia (n = 150) and Airlangga University (AU), Indonesia (n = 150). A questionnaire was distributed using Google Form via WhatsApp network. Data were analyzed using descriptive, Chi‐square, and Wilcoxon rank‐sum tests. Results All students responded (n = 300) and reported as active social media users. Majority spent ≥ 1 h a day on social media and checked their social media > 6 times a day. Most commonly used social media accounts were Instagram (UM: 92.7%, AU: 95.3%) and Facebook (UM: 94.7%, AU: 59.3%). A small proportion of UM and AU students admitted to posting clinical photographs, patient records, and comments about patients on social media. UM students had significantly better scores in terms of their professionalism behaviors on maintaining the integrity of the profession compared to AU students (p < 0.001). Meanwhile AU students had better scores than UM students on behaviors related to upholding colleagues’ professional image on social media (p = 0.421). Most students in UM and AU shared similar positive perceptions toward online professionalism behavior statements. Majority reported concerns over unprofessional posts online. Conclusion Self‐reported behaviors online sometimes contradict with students’ perceptions and concerns about being unprofessional online. There is a need for clearer educational guidelines on how to instill e‐professionalism values and behaviors among dental students.