PHOENIX — Arizona Cardinals quarterback Carson Palmer is retiring after 15 NFL seasons.
Palmer, who turned 38 last week, made the announcement in an open letter released Tuesday by the Cardinals. Palmer missed the last nine games of what would be his final season with a broken left arm.
He called his long professional career "the most incredible experience of my life."
The statement came one day after Cardinals coach Bruce Arians announced his retirement. Arians and Palmer spent the last five seasons together.
Palmer was a Heisman Trophy winner at USC and the No. 1-overall pick by Cincinnati in 2002. He threw for 46,247 yards, 12th-most in NFL history, in a career with the Bengals, Oakland and Arizona.
"When I entered the league, I was a 23-year-old kid," Palmer wrote. "I'm leaving a 38-year-old husband and father of four with memories and experiences that I will treasure for the rest of my life. And like most things in life, it feels like it all passed in a blink of an eye."
Acquired by the Cardinals for only a sixth-round pick and a swap of seventh-rounders, Palmer had some of his greatest success in Arizona.
The 2015 season may have been his best. He set single-season franchise records and career highs for yards passing (4,671) and touchdowns (35) while leading the Cardinals to a 13-3 record, second-best in the NFC. He won his only playoff game in four tries that season, in overtime over Green Bay.
Palmer twice came back from significant knee injuries.
"My family and I are beyond grateful for everything the game has given us as well as the love and support we've felt from fans everywhere we've been. That's been especially true in Arizona, where we never expected to end up but wound up being such a special place for us."
Cardinals centre A.Q. Shipley, through Twitter, congratulated Palmer on "one hell of a career."
"My favourite all-time teammate is walking away on his terms," Shipley said. "Not many people have that opportunity. It's been an honour and a privilege to block for you and be your teammate. Enjoy retirement brother!"
For more NFL coverage: http://www.pro32.ap.org and http://www.twitter.com/AP_NFL