Garrard had been on a two-week roster exemption after contacting the team two weeks ago and asking for the chance to return. Citing chronic knee pain, the former longtime Jacksonville Jaguars starter retired in May, two months after signing a one-year, free-agent contract with the Jets.
The Jets envision Garrard, 35, as a mentor for rookie Geno Smith, who has started the first seven games. Because of back and knee injuries, Garrard hasn't taken a regular-season snap since 2010.
First-year quarterback Matt Simms, who has no NFL experience, has been the primary backup. Quinn was inactive for the last six games. He was signed as an emergency quarterback in the aftermath of Mark Sanchez's shoulder injury, which turned out to be season-ending.
Garrard said he received no promises from the Jets upon his return. But he has practiced with the team and received a personalized locker, making their intentions rather obvious.
"I was able to take the whole summer off and let my body heal," he said upon his return. "I started training a couple of months ago and my knee feels great. I'm sitting at home, watching games thinking, 'Why am I at home? Why am I doing this to myself?' I didn't want to have any regrets one day."