Maj. Gen. Stephen Goldfein currently serves as vice director of the Joint Chiefs of Staff.
The $50 million contract was for Jumbotrons for the Air Force's Thunderbirds air show. Strategic Message Solutions was the winner, even though other companies had submitted lower bids, the newspaper said.
The company's partners included a recently retired Air Force general and a civilian pilot with close ties to high-ranking officers.
"The investigation found that the December 2005 award to SMS was tainted with improper influence, irregular procurement practices, and preferential treatment," the Department of Defense Inspector General said in a 251-page report.
Goldfein even recruited President George W. Bush into his effort to steer the contract to SMS, the report said. The president videotaped a tribute to the company with the White House Map Room as a backdrop.
Goldfein and other top officers involved received administrative penalties, the Post said.