Davis told Brooke Cersosimo of NFL Media he will step away from the game after the 2018 season.
Davis had said this week that he expects his role to be reduced next season, and he anticipated that it would be reduced further in 2019.
Davis missed all but nine games from 2009-2011 because he tore his ACL three times, but he has started all 78 games he has played over the past five seasons.
Davis, who turns 35 in March, was named to the Pro Bowl in 2015 and 2016, and was a first-team All-Pro selection in 2015. He was named the Walter Payton Man of the Year in 2014 for his off-field work.
Davis started all 15 regular-season games he played this past season, but his tackle total was down to 76, his lowest in a full season since his rookie year in 2005.