The extension is worth $50 million, according to Jason La Canfora of CBS Sports. ESPN's Chris Mortensen reports that contract is only guaranteed through next season and that the average salary ranges between $15.9 million and $16.6 million.
Palmer's original contract expired at the end of this season. He will be 38 years old at the end of his extension.
Palmer has played 11 seasons in the NFL and is in the midst of his second with Arizona. He led the team to a 10-6 record last season, its best since 2009. He is 5-0 as a starter this season. He missed three games with a nerve issue in his throwing shoulder.
This season, Palmer is averaging 277 yards per game and has thrown 11 touchdowns and two interceptions.
Palmer was the first pick of the 2003 draft out of USC. He was the winner of the 2002 Heisman Trophy.
- Dan Gartland