The forward had surgery to drain fluid from the adductor region of his hip Jan. 18. He was activated from injured reserve Saturday.
"I had a real bad infection in my groin that spread through the whole upper leg on my left side," Hayes said Friday. "It got to a point where surgery was needed and we did that and we waited for the infection to get out and waited for this lump that I had to settle down. I feel pretty good now."
The surgery Hayes had in January was his third since the end of the 2020-21 season. He had core muscle surgery in May and abdominal surgery Sept. 21 that sidelined him for the first 12 games of the season.
Hayes aggravated the injury in his second game back, against the Calgary Flames on Nov. 16, and missed six games. He returned Dec. 1 and played 18 games before leaving the lineup again.
He has scored nine points (three goals, six assists) in 20 game this season heading into the game Saturday (3 p.m. ET; ABC, ESPN+, SN, NHL LIVE).
Flyers general manager Chuck Fletcher said Feb. 11 that it was "50-50 he can come back and play."
Hayes had been a frequent participant in practices and morning skates prior to Saturday.
"This is the best I've felt in a while," he said. "I can just feel it skating up the ice prepractice. When you're striding and you don't feel a tug in your leg or a pain in your upper groin, it's nice. When you skate full speed without pain, it feels nice."
Coach Mike Yeo said adding Hayes to the lineup would help on and off the ice.
"It should bring some energy to the group, that's for sure," Yeo said Saturday. "You bring a guy like Hayes back into the lineup, he's a big man (6-foot-5, 216 pounds) and he's a big presence inside the locker room. Anxious to see what he can do out there today for us.
"How much we'll use him, whether we use him on the penalty kill, I think that we've got to kind of get a gauge to see where he's at. But if he's healthy then he could impact the game and help us in a lot of different ways. So we'd love to keep them in the lineup and have him do what Kevin Hayes can do. We haven't had that for a long time and obviously we've missed it as a group."
The Flyers (16-28-10) are 1-6-2 since the All-Star break and last in the Metropolitan Division. Hayes, who is in the third season of a seven-year contract worth $7.14 million annually, said he felt a responsibility to do everything he could to play, as long as it didn't jeopardize his long-term health.
"It's obviously frustrating when you see the season the team is having and you're supposed to be one of the key players to help your team win, and even when you were playing you weren't doing too much to help your team win," he said. "I take a lot of pride in helping this team win and being the best player I can be. I love playing for this team, I love playing for this city. It's been a tough year for that stuff. Hopefully that stuff is in the past and starting tomorrow can start trending in the right way."