Lynch, who renegotiated his contract before this season, is due to make $7 million next season. It has been previously reported that the team would release Lynch to save money against the salary cap.
"Mainly because he actually has outperformed his contract and clearly established himself as the identity of this team," Rapoport said. "Basically, they don't have a choice based on the way he plays to bring him back."
Rapoport also added that the 28-year-old Lynch could consider retirement, which he reportedly did after the Seahawks won the Super Bowl last season.
Lynch rushed for 157 yards in the NFC championship game on Sunday as the Seahawks beat the Packers. He finished the regular season with 1,306 rushing yards and a league-leading 13 touchdowns.
He has rushed for at least 1,200 yards in each of the last four seasons since joining the Seahawks from the Bills in 2010.
Lynch and the Seahawks will face the Patriots in Super Bowl XLIX on Feb. 1.
- Paul Palladino