"He has been found guilty. It proves that the system works no matter who you are," said Pat McQuaid, president of the international cycling union (UCI).
The 31-year-old Landis, set to become the first Tour de France winner to be stripped of his title, said in a statement: "This ruling is a blow to athletes and cyclists everywhere. I am innocent, and we proved I am innocent."
McQuaid said Oscar Pereiro, who finished second to Landis in 2006, would be declared the winner, making him the first Spaniard to win Tour de France Miguel Indurain's last victory in 1995.
"Under our regulations, Pereiro will be declared the winner of the 2006 Tour de France," said McQuaid.
The US arbitration experts decided Landis had injected himself with testosterone after lengthy deliberations following a hearing in May.