Studies have revealed that individuals' identities can be shaped not only offline but also online. However, the formation of online identity of students in higher education environments is complex. Empirical evidence has suggested that academics are interested in using social media to enhance their professional identity and reputation. The current study examined the effects of online social capital and social networking on the formation of graduate students' professional identity. Structural equation modeling was used to test the research hypotheses. The sample consisted of 298 graduate students from one leading public university and three private higher education centers in Iran. The results showed that online social networks in higher education environments could affect the construction of students' professional identity through online social capital as a mediator.