He led the Saints to their only Super Bowl after the 2009 season, when they beat the Indianapolis Colts to win the title.
"I'm only retiring from football, I'm not retiring from New Orleans. It's not a farewell, but rather a new start," he said.
Brees, who joined the San Diego Chargers in 2006, threw for 80,358 passing yards, which is the biggest in NFL history, while he also had 7,142 successes.