He was diagnosed with a chest wall contusion, according to the team.
Kemp slammed into the wall while reaching up to catch a ball hit by Wil Myers in the third inning. He threw the ball back to the infield and initially stayed in the game after trainers checked on him.
He then struck out in the top of the fourth inning and was replaced in the outfield by Scott Schebler to open the bottom of the inning.
Reds manager David Bell said Kemp “was a little dazed, but he was adamant about staying in the game” after trying to catch Myers’ drive to left.
“I knew he was in a little bit of pain,” Bell continued. “We were just hoping it was a temporary thing, but after he came back in from hitting it was pretty obvious that we needed to get him out of there.
“He’s a tough guy and he went into the wall hard and almost came up with a great catch.”
The Associated Press contributed to this report.