He started at second base Saturday with his team in the middle of a playoff race. The Tigers hope the 35-year-old can provide a boost at a position where nobody on the team has excelled this season.
Guillen hadn't played since Aug. 16, when a runner slid into him while he was trying to turn a double play, injuring his left knee.
"It's a long time. It's tough," Guillen said before the Tigers hosted the Chicago White Sox. "I'm happy to be here, to be back."
Guillen received a nice ovation from the crowd at Comerica Park when he first came to the plate in the second inning. He flied out to left field, but grounded a single to right in the fourth.
He looked fine in the field, comfortably catching a shallow fly ball in the second and ranging to his right to make a play on a sharp grounder in the fifth.
Guillen said he felt good at times during spring training, but his rehabilitation took a while.
"It's a tough injury," Guillen said. "Sometimes you feel good for one week, and the next day you're sore. Right now, I'm at the point where I've been playing 15, 20 days in a row, and I feel good every day."
Guillen hit .316 in 11 games with Triple-A Toledo.
"I've got like 10 months, I haven't played every day," Guillen said. "You need to get some at-bats, feel comfortable at the plate, feel comfortable in the field."
Detroit entered Saturday one game behind first-place Cleveland in the AL Central. Center fielder Austin Jackson was out of the starting lineup with a sore left wrist.
Manager Jim Leyland put Guillen in the lineup immediately, hitting the veteran seventh.
Guillen was hitting .273 last year when he was hurt. If he produces at that level the rest of this season, it could help the Tigers as they attempt to return to the playoffs for the first time since 2006.
"That's where you want to be -- a winning team where you have fun every day, where you're in a pennant race every day," Guillen said.