Jets coach Herman Edwards announced on Monday that Pennington, a first-round pick in 2000, will replace veteran Vinny Testaverde as the team's starting quarterback.
Pennington will make his first NFL start on Sunday when the Jets (1-3) host the Kansas City Chiefs, but he played most of the way in Sunday's 28-3 loss at Jacksonville after Testaverde was injured, completing 21-of-34 for 281 yards but failing to get the Jets in the end zone.
Testaverde suffered a bruised right shoulder after being tackled by defensive tackle Marcus Stroud in the first quarter of Sunday's loss at Jacksonville and did not return.
Edwards' decision to shake up the team is not surprising since the Jets have been outscored, 102-13, in their last three games - losses to New England, Miami and Jacksonville.
"It's not all on Vinny and I had a talk with him this morning," Edwards said. "Everyone's accountable for what's happened but most of the time the quarterback takes the first hit and Vinny understands that."
The 38-year-old Testaverde failed to complete any of his four pass attempts in Sunday's loss before suffering the injury. He is 53-of-82 for 485 yards and three touchdowns with three interceptions this season.
In his 16th NFL season, Testaverde ranks ninth on the all-time list with 39,564 yards.