Background: In recent years, new forms of media-social networking services (SNS)-such as Facebook and Sina Weibo have spread rapidly. Greater SNS use has been associated with greater body dissatisfaction, which in turn, is related to greater eating disorder (ED) symptom severity. In this study, we (1) investigated the relationships between ED tendencies, SNS use intensity, and body esteem and (2) examined the mediating role of body esteem in the relationship between SNS use intensity and ED tendencies among Japanese and Chinese students. Methods: A total of 564 Japanese and Chinese college students aged 18–22 years were surveyed on their age and BMI, including self-filling questions from the Japanese and Chinese versions of the Eating Attitudes Test (EAT-26), SNS Intensity Scale, Body Esteem Scale for Adolescents and Adults (BESAA), Patient Health Questionnaire-9 (PHQ-9), and Generalized Anxiety Disorder-7 (GAD-7) scale. Results: The proportion of students with a score of ≥ 20 on the EAT-26 was 15.8% (Japanese, 14.7%; Chinese, 17.0%). The number of participants with scores ≥ 20 on the EAT-26 was significantly higher than ever before, both in Japan and China. Chinese students reported greater body esteem than Japanese students, as well as a stronger association of SNS use intensity with body esteem. Among Japanese students, EAT-26 scores were unrelated to SNS Intensity Scale scores but had a weak negative correlation with BESAA scores; therefore, body esteem did not mediate the relationship between SNS use intensity and ED tendencies. Among Chinese students, scores on the SNS Intensity Scale and BESAA had a weak correlation with EAT-26 scores, and SNS use intensity reduced ED tendencies through greater body esteem. Conclusions: It is important to consider the way users engage with SNS, in addition to the SNS use intensity. Improving body esteem may reduce the risk of ED. Furthermore, it is necessary to include men in the discussion on ED in the future. Plain English summary: We investigated the relationships between eating disorder (ED) tendencies, social networking service (SNS) use intensity, and body esteem among Japanese and Chinese students, and compared the findings. We surveyed 564 Japanese and Chinese students regarding basic demographic information, ED tendencies, SNS use, body esteem, depression, and anxiety. The results showed that the number of participants with scores ≥ 20 on the Eating Attitudes Test was significantly higher than ever before, both in Japan and China. In Japanese students, body esteem affected ED tendencies, while SNS use intensity did not. In Chinese students, SNS use intensity reduced ED tendencies through greater body esteem. There were no gender differences in Eating Attitudes Test scores among Japanese students. This study provides evidence for the relationship between ED tendencies, SNS use, and body esteem in Asian countries. [ABSTRACT FROM AUTHOR]