De León is Loyd E. Cotsen Endowed Chair of Archaeology, Professor of Anthropology, Professor of Chicana, Chicano, and Central American Studies, Director of the Cotsen Institute of Archaeology at the University of California, Los Angeles[3] and Director of the Undocumented Migration Project,[4] a non-profit research/arts/education collective aimed at documenting and raising awareness about migration issues while also assisting families of missing migrants search for their loved ones.

Since 2009, he has traveled frequently to the Sonoran Desert in Arizona to collect artifacts left behind by migrants trying to gain access to the United States.

He received his PhD in anthropology in 2008 from Pennsylvania State University, where he completed his dissertation titled, "The Lithic Industries of San Lorenzo-Tenochtitlán: An Economic and Technological Study of Olmec Obsidian" on the many years he spent in Mexico excavating obsidian tool artifacts left by indigenous people thousands of years ago.

[10] De León's self-described areas of interest and methods include undocumented migration and deportation, human smuggling, violence, materiality, archaeology of the contemporary, photo-ethnography, and forensic science.

[9] His work has been described as a multidisciplinary approach to Latin America to US migration and involves ethnographic analysis of migrant stories, forensic science, and archaeological research.

[12] As part of UMP, De León directs Hostile Terrain 94 (HT94), a participatory art project resulting in an exhibition of 4,200+ handwritten toe tags that represent migrants who have died trying to cross the Sonoran Desert of Arizona between the mid-1990s and 2024.

From 2013 to 2017, he co-curated an exhibition of artifacts and other materials collected by the Undocumented Migration Project in a show called State of Exception that was featured in multiple locations including the Museum of Contemporary Art in Detroit (MOCAD) and the New School in New York City.

He is the author of the book The Land of Open Graves: Living and Dying on the Migrant Trail, with photos by Michael Wells, which combines the use of ethnography, archaeology, linguistics, and forensic science to document the human consequences of US immigration policy (University of California Press, 2015).