Flynn featured in five games for the Packers last season, coming in for Scott Tolzien to help his side overturn a 16-point deficit to beat the Minnesota Vikings before going 2-2 in four matches as a starter.
He was replaced for the season finale as the returning Rodgers steered the Packers to a win over the Chicago Bears that clinched the NFC North title.
However, despite throwing for 1,146 yards with seven touchdowns and four interceptions, Flynn was released by the Packers earlier this off-season.
The 28-year-old was due to visit the New York Giants, but that was called off earlier today, allowing the Packers to steal in and re-sign him for another season.
Flynn began his career with the Packers in 2008, acting as backup to Rodgers for four seasons before short stints with the Seattle Seahawks, Oakland Raiders and Buffalo Bills.
He is expected to compete with Tolzien for the role of number two quarterback next season, with head coach Mike McCarthy understood to want to keep three quarterbacks on the roster.