Beason received a three-year, $19 million deal that includes $7 million guaranteed and $12 million in the first two years, a league source told ESPN NFL Insider Adam Schefter.
The Carolina Panthers' first-round pick in 2007, Beason was a Pro Bowler in 2008, 2009 and 2010 before injuries began to wear him down.
He lost his starting middle linebacker job to Luke Kuechly in 2012, and he was a poor fit on the outside for Carolina, which traded him to the Giants for a seventh-round pick in October 2013.
The Giants immediately installed Beason as their middle linebacker, giving him responsibility for making the calls on the defense, and his new teammates accepted him and followed him as a leader.
The Giants' defense performed noticeably better over the final 11 games with Beason in the middle of it. He recorded 93 tackles in those 11 games, including 17 in the Dec. 1 road victory over the Redskins.
Beason, 29, played 15 games in 2013 after injuries limited him to a total of five in the previous two seasons.