She was born in Colombia and graduated from law school at University of the Andes before moving to New York City to do a M.S. from the Graduate School of Journalism at Columbia University. She worked as a reporter on the Wall Street Journal Americas before returning to Colombia in 1998.
Ms León worked for the newspaper El Tiempo and for Semana magazine. She was editor-in-chief of semana.com and collaborated with the TV series Tiempos difíciles and Regreso a la Esperanza. She was one of the first journalists to reveal the links between several Colombian politicians and paramilitary groups.
Ms León was the editor of Años de fuego (2001, an anthology of the best Colombian reportages from the 1990s). In 2004 she published No somos muchos pero somos machos (articles on civil resistance by Colombian indigenous people and Bogotá's ex mayor Antanas Mockus).
Her book País de plomo. Crónicas de Guerra [Country of Bullets. War Diaries] deals with Colombia's armed conflict at the beginning of the 21st century. It was released by the University of New Mexico Press in English. In 2006 she was awarded the Lettre Ulysses Award for the art of reportage (3rd prize) and was named a Nieman Fellow by Harvard University.
She taught at New York University's Graduate School of Journalism and worked as editor-in-chief of Flypmedia.com, an online news magazine based in New York City, until June 2008.
In 2014, she edited and co-authored another book on profiles of important politicians in Colombia called "Los súperpoderosos" written by her team of La Silla Vacía.
She was part of the board of Global Voices until 2015 and now is member of the Consejo Superior of the University of los Andes and president of the Board of the Free Press Foundation.
- World Health Organisation's World Prize for Health Journalism (2001, for an article on the health risks posed by the conflict in Colombia)
- Fundación para un Nuevo Periodismo Iberoamericano - Cemex journalism prize (2002, finalist)
- Lettre Ulysses Award (2006, 3rd prize for the book País de plomo. Crónicas de guerra)
- No somos machos pero somos muchos (2004)
- País de plomo. Crónicas de guerra (2005, Country of Bullets. War Diaries)