Given that there is a lack of instruments assessing internet-related addictions among Chinese population, this study aimed to validate the Chinese version of the nine-item Internet Gaming Disorder Scales- Short Form (IGDS-SF9), Bergen Social Media Addiction Scale (BSMAS), and Smartphone Application-Based Addiction Scale (SABAS) among Hong Kong university students. Participants aged between 17 and 30 years participated in the present study (n = 307; 32.4% males; mean [SD] age = 21.64 [8.11]). All the participants completed the IGDS-SF9, BSMAS, SABAS, and the Hospital Anxiety and Depression Scale (HADS). Confirmatory factor analyses (CFAs) were used to examine the factorial structures and the unidimensionality for IGDS-SF9, BSMAS, and SABAS. CFAs demonstrated that the three scales were all unidimensional with satisfactory fit indices: comparative fit index = 0.969 to 0.992. In addition, the IGDS-SF9 and BSMAS were slightly modified based on the modification index in CFA. The Chinese IGDS-SF9, BSMAS, and SABAS are valid instruments to assess the addiction levels of internet-related activities for Hong Kong university students.