Sidelined since June 22 with a bone bruise on his right knee, the All-Star center fielder was activated from the disabled list Tuesday before the opener of a three-game series against the Florida Marlins.
"It's good to be here after being out for a long time and a long rehab. I'm very happy to be back with the team," Beltran said. "Honestly, I have to monitor my knee and start slow."
His return almost certainly comes too late to help the injury-ravaged Mets salvage their season. They ended the day 16 1/2 games out of a playoff spot with 24 to play.
New York was 34-33 when Beltran went down, only two games out of first place in the NL East. Also missing Jose Reyes and Carlos Delgado for the entire stretch, the Mets went 28-42 without Beltran and fell to fourth place.
"It was tough," he said. "At one point it was like everyone was out. And honestly, this year has been like a terrible year for us."
Asked why he wanted to come back this late in the season rather than rest up for next year, Beltran had a simple answer: "Why not? I don't feel obligated. This is my job. I'm doing what I have to do. I went to rehab, I rehabbed myself. I made improvement, so I'm here."
When he was introduced before the game, Beltran received a smattering of applause from the sparse crowd at Citi Field. He struck out swinging his first time up against Florida starter Rick VandenHurk and flied out in the fourth before hitting a fly-ball double to left in the sixth.
In the seventh, Beltran brought fans to their feet. His bases-loaded drive to right field was caught a step or two in front of the fence by Cody Ross, preserving Florida's two-run lead.
"I just got under that one," Beltran said. "Today I felt like a kid in the playground, like when I take my daughter to the playground. She's having fun and that's how I felt today. I felt good."
Beltran finished 1 for 4 during New York's 4-2 loss and made a smooth, sliding catch in center.
"It will probably take him a few games to really find his rhythm at the plate," manager Jerry Manuel said. "I think once that starts he will get on track, so to speak. He looked pretty good."
Beltran, who batted cleanup, said his most recent MRI showed the bruise on his knee had decreased in size.
"I'm not really thinking about my knee right now. I'm just trying to go out there and play the game right. And if I feel something, then I have to stop and pull back," he said. "I don't expect to go out and be perfect. I have to come to the ballpark every day, prepare myself, go to the cage, try to get the timing."
Manuel said he'll keep close tabs on Beltran, likely playing the slugger a couple of days in a row, then resting him for a day, playing him three days in a row, then resting him for a day.
"It's almost kind of like a spring training type of thing. That's kind of the plan right now," Manuel said. "You have to applaud him for the effort that he's put forth in trying to get back at some point this season."
Manuel said Beltran's return can help answer questions going into spring training next year. The switch-hitter was off to a strong start before he got hurt, batting .336 with eight homers and 40 RBIs. He also had 20 doubles, 11 stolen bases and a .425 on-base percentage.
The 32-year-old Beltran went 3 for 18 with two RBIs and two walks in five rehab games with Class-A Brooklyn. He said he'll need to change his offseason conditioning program a bit, adding balance exercises to strengthen his knee and quadriceps.
He said his doctor told him an offseason of rest should heal the injury completely, so Beltran doesn't expect to need surgery.
The Mets also purchased the contract of right-hander Tobi Stoner from Triple-A Buffalo. Manuel said Stoner could pitch in relief of John Maine on Sunday at Philadelphia.
New York has scheduled Maine to start the second game of Sunday's day-night doubleheader. The right-hander, sidelined since June 7 with a sore shoulder, would likely be on a short pitch limit.
Maine threw a bullpen session Tuesday and could face a few hitters Thursday. Then, the Mets will make a final determination about whether he's ready to pitch against the Phillies on Sunday.