Judge Shira Scheindlin announced the sentencing date at a hearing in US District Court for the Southern District of New York, court sources told AFP.
"The judge rejected the motion presented by the defense," the source said. "The sentencing is set for March 12."
Bout, 45, is accused of being the biggest clandestine arms dealer in the world.
On November 2nd, Bout was found guilty on four counts of conspiring to sell missiles to terrorists and conspiring to kill American service personnel. He faces a minimum of 25 years and possibly life in prison.
Defense attorney Albert Dayan said he would appeal.
The former pilot and translator for the Soviet military was arrested in 2008 during a covert operation by US agents in Thailand, where he was jailed while awaiting extradition. He was flown to the United States in 2010 after a long legal battle that created tensions between Washington and Moscow.
Bout says he only transported arms as part of a legitimate air cargo business.
Dubbed "The Merchant of Death" by some media, Bout was accused of trying to sell to undercover agents surface-to-air missiles and other weapons. The undercover agents posed as Revolutionary Armed Forces of Colombia guerrillas who planned to use the weapons against US counter-narcotics agents.
US officials believe that Bout, who inspired the character played by Nicolas Cage in the movie "Lord of War," organized a fleet of cargo planes after the end of the Cold War to carry weapons to trouble spots in Africa, Latin America and the Middle East.
One issue that arose during the trial in Manhattan was whether it would be possible to find an impartial jury after "Lord of War" appeared in movie theaters across the United States.