BBC reports Avila, who is known as "Queen of the Pacific," admitted to "hindering the arrest" of Juan Diego Espinosa Ramirez between 2002 and 2004.
Espinosa, who was her boyfriend at the time, is the former leader of Mexico's Sinaloa cartel. He pled guilty to cocaine trafficking charges in 2009.
"Between approximately 2002 and 2004, Avila-Beltran provided financial assistance for travel, lodging and other expenses to [Espinosa] with the intention of preventing or hindering his arrest for drug-trafficking crimes," the US attorney's office said in a statement.
Avila, 52, had been incarcerated in Mexico City since 2007 where she was arrested for money laundering and drug trafficking charges. She was extradited to Miami last August.
She's currently facing a prison sentence of 15 years after reaching a plea bargain with officials. She originally denied any wrongdoing.
Avila's uncle, Miguel Angel Felix Gallardo, was known as The Godfather of drug trafficking to the U.S. in the 1980s.