Gyorko suffered a setback June 26, while on his first rehab assignment with Double-A San Antonio, when his leg tightened up and forced him to leave the game.
The Padres have handled him with caution since then. He slowly worked his way back to a second rehab assignment -- two games with Class A Lake Elsinore on Wednesday and Thursday -- where he was 4-for-7 with a double, an RBI and two runs scored.
The Padres decided after Thursday's game that Gyorko was ready.
"If he was going to play, let's play him here," said Padres manager Bud Black. "His leg feels that good."
The Padres have three games remaining before the All-Star break and Gyorko thinks that had a factor into the decision for him to be activated now. After Sunday, he'll be able to take some time off to rest his legs.
The Padres will be glad to have him back. Before Gyorko's injury, he was one of their hottest hitters with a .284 average, eight home runs, 25 RBIs and 36 runs scored.
They have been scuffling recently as well, losing 12 of their last 13 games.
"It's tough to sit there and watch," Gyorko said. "We obviously want to be out there and help. When you get on the disabled list and get hurt, you know that there's not a whole lot you can do. It definitely gets frustrating."
Now the Padres' lineup is a lot more formidable with the return of Gyroko and first baseman Yonder Alonso.
"This is closer to the lineup we expected to have," Black said. "When they're all doing what they are capable of doing, we think offensively this is a lineup that's going to be productive."
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. Jamal Collier is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.