Griffey's mother was to undergo colon cancer surgery Thursday. Griffey decided to play in Thursday's game against St. Louis and homered in the seventh inning off Jeff Weaver. He went 2-for-4 in the Reds' 2-1 loss.
Before the game, Griffey had said it would be a game-time decision on whether to play.
"It's up to her," Griffey said in The Cincinnati Enquirer. "If she wants me [in the lineup], I'll be there."
Griffey's mother was to have surgery in Orlando, Fla. His father, former major leaguer Ken Griffey Sr., is suffering from prostate cancer. Griffey found out about his father's condition 1½ weeks ago.
Griffey's parents are divorced.
"Not one parent, but both your parents," he said in The Enquirer. "It's been tough."
Reds manager Jerry Narron said Griffey has given Griffey permission to leave the team if he wants.
"I talked to him about taking Monday and Tuesday," Narron said. "He didn't want to do it. I think his mother doesn't want him to."
Griffey was hitting .246 after Thursday's game.
"He wouldn't be human if it didn't affect him," Narron said.