The contract reportedly is for one-year, $900,000.
The Flyers last week traded Sergei Bobrovsky to the Columbus Blue Jackets, opening the No. 2 spot behind Bryzgalov.
"I'm very happy to be back in Philly," Leighton said, according to the team's website. "This is where I want to be and I'm excited about the team we have this year. I look forward to the opportunity to continue working with Jeff Reese."
Leighton, 31, has not played an NHL game since 2010-11, when he played one.
In parts of three seasons, all with the Flyers, he is 35-40-2 with a 2.95 goals-against average and .902 save percentage in 104 games.