The A's had expected Gray to be shut down for three weeks, but Gray got the OK after visiting Dr. Anthony Romeo in Chicago.
"Everything looked good," Gray told SFGate.com on Tuesday. "He said, 'Go ahead and start throwing when you get back,' so that's what we're going to do. We'll see how it goes.
"I'm excited to go out there and throw a baseball. It'll be good to be out there."
Gray was eager to start fresh after a forgettable 2016. He was scratched from his scheduled outing Opening Day last year because of food poisoning and didn't have the kind of season he had envisioned as the leader of the rotation.
"It was good news, definitely," manager Bob Melvin said of the decision for Gray to resume throwing. "Mentally and physically, this is good for him. No real plan, just go day by day."
He spent two stints on the DL and went 5-11 with a 5.69 ERA on the heels of back-to-back 14-win campaigns. Gray, who received a $3,575,000, one-year contract to avoid arbitration, initially had plans to pitch for the U.S. in the World Baseball Classic.
The Associated Press contributed to this report.