His management firm shared his statement.
Harris spent his first 10 seasons with the Jets after being chosen with the 47th pick of the 2007 draft.
He joined the Patriots on a two-year, $5-million contract ahead of the 2017 campaign, but spent just the one season with his former AFC East rival. The 34-year-old played 10 games in the regular season and none in the playoffs.
Harris totaled 1,110 combined tackles, 37 sacks, 11 forced fumbles, and six interceptions over 164 regular-season games.