Abstract This article aims to provide insight into the formation of religious identity among the millennial generation of the Indonesian Muslim diaspora in the Netherlands, identifying its main influencing factors. Our empirical study identified a dynamic and diverse process regarding the formation of the millennial group’s religious identity, expressed dynamically in various aspects of Islamic teachings at the level of religious beliefs, morals or ethics, and practices. The negotiation process between their Islamic and Western identities produced various identity statuses, namely diffusion, foreclosure, moratorium, and achievement. The process shifts between exploration and commitment. The study concludes that religious identities formed through exploration are more established and more adaptable to environmental changes than those based on commitment with no exploration. Second, the formation of the Indonesian Muslim millennial diaspora’s religious identity is influenced by three key factors, namely social environment, reference groups, and role models.