Rivera, 43, tore his right anterior cruciate ligament during batting practice in Kansas City in May and underwent knee surgery.
He told MLB.com during a charity event at Yankee Stadium Wednesday he threw off the mound for a commercial recently and the leg felt good.
"My arm is good. Everything else is good, so I will start throwing the baseball pretty soon," the closer said. The Yankees open the 2013 regular-season at home against the Boston Red Sox April 1.
Rivera, who leads Major League baseball in all-time saves with 650, signed a one-year, $10 million contract with the team and said he would be "definitely ready" to pitch in Spring Training.
"The leg is getting stronger, and that's it" he said. "You have to give it time. I'm doing my part. It isn't quite there yet."