The Hawthorne space company is scheduled to launch the GPS III satellite in February 2019 from Cape Canaveral Air Force Station in Florida.
The satellite will provide better anti-jamming capabilities and improved accuracy for precision navigation and timing, according to the Air Force.
SpaceX President Gwynne Shotwell said in a statement that the company was proud to be selected for this contract.
"We appreciate the confidence that the U.S. Air Force has placed in our company," she said.
SpaceX was certified by the Air Force in 2015 to launch national security satellites, breaking up a longtime and lucrative monopoly held by a joint venture of Boeing Co. and Lockheed Martin Corp. called United Launch Alliance.