At the transition to higher education, students from diverse backgrounds develop peer networks that support learning in higher education. However, few studies have investigated how students' background characteristics play a role in social selection mechanisms such as friendship and help-seeking and what drives the formation of diverse peer networks, including the role of students' sense of belonging in higher education. We studied how students' migration background and generation in higher education-status affect peer network development at the transition to higher education and how sense of belonging plays a role in the development of diverse peer networks. In total, 247 first-year higher education students filled out surveys at three times during the first semester at the transition to higher education. Longitudinal complete social network data on students' friendship and help-seeking relationships in the course programme were analysed using stochastic actor-oriented modelling. At the start of the academic year, continuing-generation in higher education students and students with a strong sense of belonging were more active with building relationships. Students were more likely to connect to others with a similar migration background. At later stages of the transition to HE, students who scored high on sense of belonging were more likely to seek help from each other. Our findings underscore the importance of students' background characteristics in the development of friendship and help-seeking networks. Furthermore, we provide first evidence that sense of belonging plays an important role in the formation of peer networks.