Emerging evidence suggests that the COVID-19 pandemic has extracted a substantial toll on immigrant communities in the United States, due in part to increased potential risk of exposure for immigrants to COVID-19 in the workplace. In this article, we use federal guidance on which industries in the United States were designated essential during the COVID-19 pandemic, information about the ability to work remotely, and data from the 2019 American Community Survey to estimate the distribution of essential frontline workers by nativity and immigrant legal status. Central to our analysis is a proxy measure of working in the primary or secondary sector of the segmented labor market. Our results indicate that a larger proportion of foreign-born workers are essential frontline workers compared to native-born workers and that 70 percent of unauthorized immigrant workers are essential frontline workers. Disparities in essential frontline worker status are most pronounced for unauthorized immigrant workers and native-born workers in the secondary sector of the labor market. These results suggest that larger proportions of foreign-born workers, and especially unauthorized immigrant workers, face greater risk of potential exposure to COVID-19 in the workplace than native-born workers. Social determinants of health such as lack of access to health insurance and living in overcrowded housing indicate that unauthorized immigrant essential frontline workers may be more vulnerable to poor health outcomes related to COVID-19 than other groups of essential frontline workers. These findings help to provide a plausible explanation for why COVID-19 mortality rates for immigrants are higher than mortality rates for native-born residents.