Two weeks after suffering a concussion, Foles will start in place of Michael Vick, who is out for the second time this season with a hamstring injury. Rookie Matt Barkley will be Foles' backup vs. Oakland (3-4).
Eagles coach Chip Kelly made the announcement Wednesday after watching Foles take part in Tuesday's practice.
"Nick did really well," Kelly said. "I know he was cleared, but just because he was cleared, we (still) really needed to see him. I hadn't really had a chance to visit with him, so to get to watch him on the field, I was really happy with the way Nick practiced."
Philadelphia (3-5) is still just one game out of first place in the NFC East.
"That's one of the good things about practicing Tuesday is that you can kind of get a chance to get your eyes on people who have been out," Kelly said. "Nick is going to be our starter this week and he'll take the reps with the ones."
Foles, a third-round pick in 2011 out of the University of Arizona, suffered the concussion in the second half of a 17-3 loss to the Dallas Cowboys Oct. 20. He started that game in place of Vick, who was out with his first hamstring injury.
Vick, who missed two games, returned last week and started in a 15-7 loss to the New York Giants, but re-injured the hamstring and left in the first half. Barkley has relieved Foles, against Dallas, and Vick, against New York.
"Mike's hamstring is the same as it was," Kelly said. "We don't see him being able to go this week."
Foles has appeared in five games this season, two as a starter, and has completed 52 of 90 passes for 622 yards with six touchdowns. He has not thrown an interception, and has a 101.3 rating.
Foles came off the bench for Vick in a win over the Giants at the Meadowlands, and threw for 197 yards and two touchdowns in a 36-21 win.
A week later, he started and completed 22 of 31 passes for 296 yards and three touchdowns in a 31-20 win over the Tampa Bay Buccaneers that earned him NFC Offensive Player of the Week honors.
In his most recent start against Dallas, though, he suffered through a miserable 11-for-29, 80-yard effort before the concussion knocked him out of the game.
"I just did not play well," Foles said. "There's no reason. I just did not play well. It's going to make be better. I'm going to get better because of it."
In his rookie year, Foles started six games in place of an injured Vick and played to a rating of 79.1. He completed 161 of 265 passes for 1,699 yards with six touchdowns and five interceptions.
"I feel very confident," Foles said. "Same confidence I had after the Tampa Bay game. You feel emotions, you are human. You play bad, you let everyone down."
Kelly has that same confidence in his quarterback.
"That's one of the things I love about Nick, there's resiliency to him," Kelly said. "I know Nick didn't play well in the Dallas game. He understands that. Nick wasn't the only one who didn't play well against Dallas.
"I've seen Nick play well. I've got a ton of confidence in Nick."