The 32-year-old outfielder sustained a tight right hamstring while scoring from first on Giancarlo Stanton's RBI double in the third inning. In the fourth inning, Colorado's Michael Cuddyer doubled to left and Kearns had a tough time moving to the ball.
Miami substituted Chris Coghlan in left field for Kearns, who had a walk, single and run scored. The club said Kearns is day to day.
A non-roster invitee in Spring Training, Kearns gradually won over the organization, and he beat out Aaron Rowand for the right-handed-hitting backup outfield spot.
"He got lucky he got hot for three days, because he was my first release, when we had the meetings," manager Ozzie Guillen said. "When I saw him swing the bat, I was like, 'Wow!' It's different. He prepares himself different than anybody else. Then, I think he got a couple of nice at-bats.
"Obviously, Rowand was struggling. We needed a guy off the bench, a right-handed hitter, professional hitter, who could go out and help us. That's the reason he made this ballclub."
Kearns has been an unsung, yet big pickup for the Marlins.
The 32-year-old raised his batting average to .362 with three home runs and nine RBIs after collecting four hits in Monday's 7-4 win over the Rockies at Marlins Park.
Kearns enjoyed a solid spring, and ended up easily winning a roster spot.
"If I could have cut people, he might have been the first one to go out," Guillen said. "We had to let him play because of the problem we had. He beat Rowand easily. He earned the spot."
A Lexington, Ky., native, Kearns was the first-round Draft pick of the Reds in 1998. Had he not gone pro at that point, he was prepared to attend the University of Florida.
The Gators back then had outfielder Brad Wilkerson, who also was from Kentucky. Wilkerson went on to have a productive MLB career.
"Brad Wilkerson was down there," Kearns said. "He was playing there at the time. He was from Kentucky. He was my host. I just went down there and I just loved it. I felt like that was the place for me."
But being the seventh overall pick was too attractive for Kearns to bypass signing with Cincinnati.