League sources told ESPN NFL Insider Adam Schefter on Saturday the deal is for $7.75 million, including $4 million in 2012. Schefter reported the deal earlier Friday.
The 36-year-old Saturday, who played an instrumental role in helping to end last year's lockout, joined the Indianapolis Colts for the 1999 season, and within a year he became their regular starting center until last season. He has started 188 regular-season games in 13 NFL seasons.
This offseason, Saturday wasn't in the team's plans for 2012 -- at least on the field. According to league sources, the Colts told Saturday they would be willing to give him a front-office job.
Packers coach Mike McCarthy and quarterback Aaron Rodgers both have spoken highly of Wells over the past two seasons. He has been the team's most consistent offensive lineman and played a critical role in dictating blocking schemes.
The addition of Saturday, with his experience in the Colts' complex offense with Manning, should make for a relatively smooth transition.
It's an uncharacteristic play for a relatively high-profile free agent by Packers general manager Ted Thompson, who built the Packers into consistent contenders primarily by drafting and developing players. Green Bay may still look for a long-term answer at center in next month's NFL draft to learn the position behind Saturday.
Green Bay did not immediately confirm the deal for Saturday.
Colts owner Jim Irsay wished Saturday well.
"I wanted him to work for (the) team full time but he wanted to go at it one more year ... He's as good of a man as it gets," Irsay wrote on his Twitter account.
Saturday had been the Colts' full-time starting center since 2000. He became a fan favorite, a key figure in the NFL Players Association and one of Manning's closest friends. He visited Green Bay and Tennessee, and there had been speculation he could rejoin Manning in Denver. Saturday also thought about retiring.
Anticipating Saturday's departure, the Colts signed free-agent center Samson Satele to a three-year contract worth $10.8 million, with $5 million guaranteed. Satele has started 74 career games with the Miami Dolphins and Oakland Raiders.
Information from The Associated Press was used in this report.