Background: Immigrants in Western countries have been particularly affected by the COVID-19 crisis.Objective: We analysed excess mortality rates among the foreign-born population and changes in their distinctive mortality profiles ("migrant mortality advantage") during the first pandemic wave in France.Data and methods: Deaths from all causes in metropolitan France from March 18 to May 19, 2020 were used, with information on sex, age, region of residence and country of birth. Similar data from 2016 through 2019 were used for comparisons.Results: During the pre-pandemic period (2016-2019), immigrant populations (except those from Central and Eastern Europe) had lower standardized mortality rates than the native-born population, with a particularly large advantage for immigrants from sub-Saharan Africa. In the regions most affected by COVID-19 (Grand-Est and Île-de-France), the differences in excess mortality by country of birth were large, especially in the working-age groups (40-69 years), with rates 8 to 9 times higher for immigrants from sub-Saharan Africa, and about 3 to 4 times higher for immigrants from North Africa, from the Americas and from Asia and Oceania relative to the native-born population. The relative overall mortality risk for men born in sub-Saharan Africa compared to native-born men, which was 0.8 before the pandemic, shifted to 1.8 during the first wave (0.9 to 1.5 for women). It also shifted from 0.8 to 1.1 for men from North Africa (0.9 to 1.1 for women), 0.7 to 1.0 for men from the Americas (0.9 to 1.3 for women), and 0.7 to 1.2 for men from Asia and Oceania (0.9 to 1.3 for women).Conclusion: Our findings shed light on the disproportionate impact of the first wave of the pandemic on the mortality of populations born outside Europe, with a specific burden of excess mortality within the working-age range, and a complete reversal of their mortality advantage.