If confirmed by the Senate, Dempsey would replace Admiral Mike Mullen as chairman of the Joint Chiefs of Staff when he steps down on October 1.
At a White House ceremony, Obama hailed Dempsey as "one of our nation's respected and combat-tested generals."
Obama made the choice for the high-profile post just before heading to Arlington Cemetery for a Memorial Day event to honor America's war dead.
The selection comes as Obama is facing growing pressure to accelerate a troop drawdown in Afghanistan and is preparing to complete a withdrawal from Iraq.
Echoing remarks Dempsey himself recently made to U.S. troops, Obama vowed: "We will provide whatever it takes to achieve our objectives in the current fight."
Great website to make big money online.