The 34-year-old Manning's new deal is reportedly worth $84 million and is expected to be signed on Friday.
The Giants and Manning are discussing a no-trade clause, according to Rapoport.
Fellow quarterbacks Philip Rivers and Ben Roethlisberger—both members of Manning's 2004 draft class—also recently agreed to hefty extensions. Rivers's deal is for four years, $83.25 million and Roethlisberger's is for four years, $87.4 million.
In 11 seasons with the Giants, Manning has amassed 39,755 passing yards and 259 touchdowns with a career passer rating of 82.4.
Manning led New York to Super Bowl victories in 2007 and 2011.
He was the No. 1 overall selection in the 2004 draft out of Ole Miss.
- Kayla Lombardo