As migration is an important social phenomenon, the present study analyzes the influence of migration on migrant students' performance in mathematics. In a secondary analysis of data from Program for International Student Assessment 2012 (PISA), the mathematics achievements of students from three top-performing East Asian metropolitan areas were examined with reference to their migration backgrounds. The findings show that there is a close relation between the migration policy of the receiving system and the mathematics achievements of migrant students, with the migrant status being of advantage in one case (Singapore) and of disadvantage in two cases (Shanghai and Hong Kong SAR). These results suggest that it is important to separate the different types of migrants while relating these types with the corresponding migration policies of the receiving system and the mathematics achievement.