The Cavaliers were eliminated by the Boston Celtics, 94-85, on Thursday night in Eastern Conference semifinals.
"I missed 360 games because of injury in my career, so by my calculations I still have 3.7 years left," O'Neal told the Plain Dealer. "That means I'm going to play until I'm 41. I've been here 17 years but I've missed a lot of games, so I still feel I can play this game."
O'Neal said he'd return to the Cavaliers but many things are up in the air, including the status of LeBron James and coach Mike Brown.
"There are a lot of free agents on the team," he told the newspaper. "We just have to sit back and I'm sure everybody's going to do what's best for them."
O'Neal missed the final six weeks of the regular season after tearing a ligament in his right thumb.
"I got injured, came back in better shape," O'Neal told the Plain Dealer. "I did everything they asked me to do."