Previous studies have indicated that mobile social apps have crucial implications for social connectedness among college students, the specific patterns of WeChat usage that facilitate freshmen's college adjustment and academic performance still remain unclear. To fulfil this identified study gap, the current research thoroughly examined the dynamic associations between distinct patterns of WeChat interactions, school connectedness, college adjustment, and perceived academic performance among freshmen. Anonymous self-report online survey data from college students in mainland China supported the conceptual model, revealing that habitual use of WeChat and time spend on WeChat have positive associations with school connectedness. Additionally, habitual use and time spend on WeChat were directly correlated with academic performance and college adjustment. Furthermore, the association between WeChat usage, college adjustment, and academic performance was moderated by school connectedness. Obtained results may offer a more comprehensive portrait of how newly emerging mobile social apps could foster college adjustment and academic performance in contemporary mobile media-saturated settings.