O'Neal came off the bench and finished with five points and five rebounds against the Indiana Pacers, who won 96-94.
"It's good to be out there with the guys, but obviously there's a lot of rust," O'Neal said. "The rust will wear off and I'll get my rhythm back."
O'Neal, a key component to the Heat's NBA title run last season, had surgery on Nov. 19. The 7-foot-1, 325-pound (146-kilogram) center had played in only four games before he was injured, averaging 14 points and 7.5 rebounds.
The Heat have struggled without O'Neal, their record falling to 19-23, reports AP.
Despite the loss, Dwyane Wade was happy to have O'Neal back in the lineup.
"We're a much more powerful team with him," Wade said.
The head of Russian Technologies, Sergei Chemezov, clarified the fate of anti-aircraft guided missiles that Russia was supposed to deliver to China
The Basmanny Court of Moscow arrested Michael Calvey, the founder of Baring Vostok investment fund, on allegations of embezzling 2.5 billion rubles from Vostochny Bank. Calvey will be held in custody until April 13