The purpose of this study is to determine the effect of perceived ubiquity, perceived informativeness, perceived personalization, and mobile app usefulness on mobile app WOM on Tiket.com mobile application users in Jakarta. The samples obtained in this study were 194 respondents with a purposive sampling method through distribute questionnaires online. This study uses the SEM statistical analysis method with the Smart PLS 3.0 program as a test tool. The results of this study show perceived ubiquity, perceived informativeness, and perceived personalization have an effect on mobile app usefulness. The mobile app usefulness also have an effect on the mobile app WOM.