Online to offline (O2O) is an emerging type of e-commerce strategy that draws customers from online channels to complete purchases in offline stores. It is based on mobile services and interactions between users and merchants through information communications technology. O2O services are convenient to use as they are available anytime and anywhere and allow businesses to communicate in real-time to attract customers. Based on the S-O-R framework, this study is to empirically examine how interactivity leads to loyalty to a certain O2Oservice (i.e., mobile taxi hailing app). More specifically, relationships among interactivity-related stimuli (control, communication, and responsiveness), organismic states (engagement and satisfaction), and favourable response (loyalty toward an O2Oservice) are postulated in the research model. In order to verify the proposed model, this study employed a partial least squares (PLS) method and analysed with 257 survey samples collected from one of the most popular O2Oservices in South Korea (i.e., Kakao Taxi). As a result, all hypotheses except one are supported. Communication had a significantly positive effect on engagement, while its effect on satisfaction was not significant. Loyalty toward an O2Oservice occurs in the active interaction of users with mobile O2Oplatforms. In order for users to be engaged and satisfied with an O2Oservice, it is confirmed that the three elements of interactivity should be considered major factors.