Flacco was re-examined and his progress from a back issue "is good," according to a statement from the team.
The 32-year-old has been sidelined since July 26, when the full team reported to camp.
Veteran backup Ryan Mallett is the starter until Flacco returns. Dustin Vaughan and Josh Woodrum are the other quarterbacks on the roster.
Flacco threw for 4,317 yards with 20 touchdowns and 15 interceptions last season. For his career, he has thrown for 32,639 yards with 182 touchdowns and 117 interceptions. He also has a 61.5 percent completion percentage and an 84.5 passer rating for his career.
The Ravens also announced Friday that starting left guard Alex Lewis (shoulder) and receiver-returner Tim White (thumb) will miss the regular season.