This study investigates how the attributes of online social platforms (e.g., open vs. closed, symmetric vs. asymmetric social networks) and user preferences regarding platform diversity (e.g., single-homing vs. multi-homing) moderate the influence of homophily on user behaviors across varied social segments. On the basis of panel data, we delve into the interplay among homophily, structural diversities across various online social networking services (SNSs), and users’ homing preferences in such social platforms. The data feature of the SNS consumption behaviors of 10,172 individual users are obtained over a period of 134 days. An agent-based simulation model is developed to further validate and generalize the empirical findings. The simulation and empirical results consistently indicate that propensity toward homophily differs significantly across platform types and users’ channel adoption behaviors. Online homophily is more pronounced in closed, private social networks than in open, public social networks. Users of asymmetric and symmetric SNSs exhibit weak and strong homophily, respectively. Moreover, whereas users who adopt a single SNS channel tend toward homophily, those who subscribe to multiple SNSs confirm the idea that “opposites attract.” These findings suggest that users of online SNS channels manifest complex human interactions typified by the combination of homophily, heterophily, and asymmetric social preference, although homophily is the most prominent disposition. Our findings suggest that homophily should be considered a dynamically changing human characteristic rather than a static attribute, and stakeholders should exploit the complex nature of users’ homophilous behaviors to address social problems in online SNSs and to enhance the effectiveness of social advertising.