To make room for Conforto on the roster, the Mets designated outfielder Rajai Davis for assignment. Davis had a memorable debut for the Mets on Wednesday, arriving in the third inning after being called up from Triple-A and hitting a three-run home run in his first at-bat.
Conforto had been participating in baseball activities over the past two days and cleared MLB's concussion protocol. He had been sidelined since suffering a concussion on May 16 against the Nationals.
Mets manager Mickey Callaway said Conforto is "full go" with no limitations.
Conforto, 26, is batting .271 with nine home runs and 21 RBIs this season. He started in right field and batted third in the lineup Sunday against Tigers right-hander Spencer Turnbull, going 0-3 and being hit by a pitch in the Mets' 4-3 victory.
Davis, 38, had two hits in seven at-bats in four games since he was called up.
Callaway said the Mets hope that no other team claims Davis and that he remains in the organization. He said it was a tough decision to cut Davis, but the Mets wanted to take a longer look at newly acquired outfielder Aaron Altherr.
"I signed here to play here," Davis said as he packed his bag inside the clubhouse.
"I'm playing," he said. "Nothing wrong with me."
The Associated Press contributed to this report.