Griffin's status has been in doubt -- although he has consistently said he'd be ready to play by the NFL's first week -- since he underwent surgery in January on his right knee to repair the lateral collateral and anterior cruciate ligaments. Griffin didn't play in any of the Redskins' pre-season games.
He was cleared to play last week by his surgeon -- Dr. James Andrews -- and Monday Shanahan confirmed Griffin would be back under center when the Redskins play the Philadelphia Eagles at home Monday.
"I feel very good where Robert's at and he'll be our starter on Monday night unless there's some crazy setback that we don't anticipate," Shanahan said.
"If we didn't feel like Robert was full-go and he wasn't ready to play and do all the things that you ask a guy to do, then he would not be playing in this game.
"We believe he can do everything that a quarterback is asked to do and if that's sprinting out, if it's running the option, if it's dropping back, we think he can do all those things because he's proved it to us in practice and there hasn't been a setback so that's been a great sign."
Griffin, 23, was voted the Pro Football Writers' Offensive Rookie of the Year after last season in which he led Washington to the NFC East Division title with a 10-6 record. Griffin was injured in a late-regular season game against Baltimore and the knee problem worsened in a playoff game versus Seattle.
He completed 258-of-393 passes for 3,200 yards and 20 touchdowns while throwing five interceptions last season. He also ran the ball 120 times for 815 yards and seven touchdowns.