Jackson was a restricted free agent who was given a one-year tender worth $1.176 million.
He served in a backup role to Favre last season and appeared in eight games. The fifth-year team veteran has 19 career starts with 21 career touchdowns passing and four rushing.
A second-round pick out of Alabama State in 2006, Jackson became the Vikings' first-string quarterback in 2007. He started all 12 games in which he appeared, missing the other four with a variety of injuries: strained groin, broken finger and a concussion. He also has had knee problems during his career.
He struggled in his only playoff appearance, after the 2008 season, going 15 for 35 for 164 yards in a loss to Philadelphia.
Vikings coach Brad Childress has said if Favre decides to retire he is content going with Jackson or the other backup quarterback, Sage Rosenfels.
Minnesota has one unrestricted free agent who has not yet signed his contract tender: defensive end Ray Edwards.