Arellano-Felix, nicknamed "El Tigrillo" (Little Tiger), was arrested by the US Coast Guard in August last year while fishing in international waters off Mexico's coast.
US authorities alleged he was the head of the Tijuana drug cartel, which has been blamed for the murder and torture of police officers, informants and rivals and is one of the main smugglers of cocaine into the United States.
According to Mexican authorities, Arellano-Felix was also involved in the 1993 assassination of Roman Catholic cardinal Juan Jesus Posadas Ocampo at Guadalajara airport.
The Tijuana cartel distributes illegal drugs, much of it cocaine from Colombia, to the US state of California. Authorities say the group has diversified to include amphetamines and marijuana.
A US indictment for 11 top members of the group unveiled in July 2003 charged them with racketeering, conspiracy to import and distribute cocaine and marijuana, and with money laundering.
The 2003 indictment said the Tijuana operation received multi-tonne shipments of cocaine by sea and air from other traffickers, including Colombia's rebel Revolutionary Armed Forces of Colombia (FARC), and then arranged to smuggle the drugs into the United States.
It also said the group "recruited, trained and armed groups of bodyguards and assassins responsible for protecting the leaders of the organization and for conducting assassinations of rival drug traffickers."
Arellano-Felix pleaded guilty on Monday in a deal brokered with justice officials after they indicated they would not seek the death penalty.
The narcotics kingpin also agreed to forfeit 50 million dollars he made from his drugs empire as well as a 43-foot yacht called the Dock Holiday as part of the plea agreement.
A co-defendant, Manuel Arturo Villareal-Heredia, 31 -- a senior lieutenant within the cartel -- also pleaded guilty to racketeering and conspiracy to invest and reinvest illicit drug profits.
Villareal-Heredia agreed to forfeit five million. He faces up to 30 years in prison when he is sentenced on January 7.
