Karla Cornejo Villavicencio describes herself as a freelancer, not a journalist, because she is so intimately involved in the stories she reports through her writing. She was born in Ecuador and lived there until her parents, who had previously immigrated to the United States, brought her up to live with them and receive an American education. They raised her and her younger brother in New York City. She attended private school due to the support of benefactors. She then became likely one of the first undocumented students to attend and graduate from Harvard University and went on to pursue a PhD in American Studies at Yale University.

Though The Undocumented Americans is her first published book, she has written about her experiences, the wider world of undocumented immigration, mental health, beauty, and other topics in publications such as The Atlantic, The New York Times, The New Republic, Elle, Vogue, and others.

Villavicencio is open about her family history and her struggles with trauma and mental illness in her writing. She also openly reflects on her love for her partner, Talya, and their dog. Her work is infused with and ruminates on her personal experiences and puts them in conversation with larger contexts related to policy, economy, and culture.