Indonesia's strategic position makes it one of the transit countries for refugees in the ASEAN region. However, limited resettlement quotas provided by third countries have made Indonesia an accidental home for refugees. Some refugees are forced to stay in Indonesia for a long time, which then creates social interactions between refugees and Indonesian people in their daily activities. As a result, the phenomenon of mixed marriages between Indonesian citizens and refugees in Indonesia is something that is often found in society. The situation of refugees as a vulnerable group cannot limit their human rights to marry and have a family. However, as a country that is not a party to the 1951 Convention on the Status of Refugees, Indonesia does not yet have a legal protection that regulates refugees as legal subjects in a mixed marriage comprehensively. This situation then gave rise to various legal issues related to the legality of marriage and its implications. The large number of refugees with undocumented backgrounds who find it difficult to prove their citizenship makes it difficult for some refugees in Indonesia to fulfil the formal and material requirements of marriage, which then has an impact on not being able to register the marriage. By using a juridical-normative method, this research will discuss the legality of mixed marriages between Indonesian citizens and refugees in Indonesia from the perspective of Indonesian private international law and Indonesian marriage law. This paper will examine further the possibility of applying the principle of habitual residence to determine the law that applies to refugees who marry Indonesian citizens in the absence of laws governing people with certain citizenship conditions in Indonesia. The application of itsbat nikah in mixed marriages between Indonesian citizens and refugees in Indonesia as a solution to register marriages will also be discussed in this study. As mixed marriages that is difficult to register, legal protection for the parties to the marriage needs to be prioritized by considering the good faith of the parties.