This paper examines the roles of family in migrant entrepreneurs’ opportunity development. We employ the opportunity development and family embeddedness for theory building purposes. We conducted a longitudinal inductive case study on four cases of migrant entrepreneurs who have established businesses in Sweden and who have their origins in Lebanon and Syria, Cameroon, and Mexico, documented with 29 interviews and field observations. The paper identifies families embedding occurring by means of three norms of reciprocity and obligations that facilitate the opportunity development process. These norms are fulfilling the expectations of family and the existing family business, regularly interacting with family and the existing family business, and deploying family and business loyalty. These norms are connected to specific sub-processes of opportunity development, namely, the generation of an entrepreneurial idea, shaping an entrepreneurial idea, and defining the (new) family venture offering. By identifying these norms in the opportunity development processes, we theorize that migrant entrepreneurs rely on different family members and the existing family business from the home or host country at different moments of the opportunity development process. Such dynamic creates different norms of reciprocity and obligations for migrant entrepreneurs and their families, which influence the opportunity development.