Palmer missed the second half of the season because of a broken arm after taking a hit against the Los Angeles Rams in London. He played seven games for the Cardinals in 2017, and threw for seven touchdowns with nine interceptions before being injured.
Backup quarterbacks Drew Stanton and Blaine Gabbert split playing time for the Cardinals for the rest of the season. But Stanton and Gabbert, along with backup QB Matt Barkley, are all set to become free agents, meaning the Cards do not have a quarterback under contract for the 2018 season.
Palmer's decision to retire will save the Cardinals $14 million in salary cap space next season, according to Kyle Odegard of AZCardinals.com.
Palmer was drafted with the first pick in 2003 by the Cincinnati Bengals and played for them for eight seasons before being traded to the Oakland Raiders.
After two seasons with the Raiders Palmer was traded to the Cardinals in 2013 and played five seasons with the team. He finishes his career 12th on the all-time passing touchdowns list for NFL quarterbacks (294 TD’s) and 12th on the all-time passing yards list (46,247 yards).
Palmer is one of four players in NFL history to throw at least 100 touchdown passes for two different teams. One of the others to do so is former Cardinals QB and Pro Football Hall of Famer Kurt Warner.