As an amateur, de León won a bronze medal in the flyweight division at the 1999 Pan American Games, and was a member of the 2000 Mexican Olympic team in the featherweight division.He was trained by Vicente Juárez.

[4] He has defended his WBO junior featherweight title eight times against Gerson Guerrero, Reynaldo Lopez, Sod Kokietgym twice, Al Seeger, Gerry Peñalosa, Rey Bautista and Eduardo Escobedo.

[5] On June 7, 2008 Ponce de León was defeated by technical knockout in the first round by Juan Manuel López, losing his WBO Super Bantamweight title.

De León was the headliner of a sold out Golden Boy show[6] and inched closer to another world title shot by knocking out Puerto Rican, Orlando Cruz.

[7] Daniel defeated Cornelius Lock on May 1, 2010 the undercard of Floyd Mayweather vs. Shane Mosley[8] in the MGM Grand Garden Arena on HBO PPV to retain his WBC Latino featherweight title.