The 25-year-old tested positive for a steroid on 29 December.
Jovanovic, a pusher on the top four-man American bobsleigh team, was tested during the United States Olympic Trials in Park City, Utah.
But he immediately protested his innocence.
He claimed he accidentally took a banned steroid in a nutritional supplement, saying: "I've never taken any illegal performance-enhancing substances and never will.
"They know I didn't and they're still trying to ban me."
The suspension was announced on Wednesday by an American Arbitration Association panel after a hearing at which Jovanovic testified that he used 31 different nutritional supplements.
Jovanovic's lawyer said he would appeal the suspension to the International Court for Arbitration in Sport, which scheduled a hearing for next Wednesday, two days before the start of the Games.
While the nine-month suspension was relatively light and removed "the taint of doping" from Jovanovic, attorney Adam Driggs said his client was seeking more.
"It's troubling," Driggs said. "He is happy they gave him a light sentence, but that wasn't his goal and it wasn't our goal when we went to this hearing.
"It was to get him into the Olympics where he belongs."