Seminoles coach Jimbo Fisher said Monday that Francois is scheduled for surgery Tuesday and the timeline for his recovery is four to seven months.
"He's very disappointed," Fisher told reporters. "Not only does he want to play, he wants to be with his teammates."
Late in the fourth quarter, Francois was sacked from behind by Crimson Tide safety Ronnie Harrison. Francois stayed on the turf after clutching his left knee. He was helped to his feet by trainers, but he couldn't put any weight on his leg while leaving the field.
Francois was taken to a medical tent on FSU's sideline and emerged with a heavy brace on his left leg. He was using a pair of crutches.
Freshman James Blackman, from Belle Glade, Florida, replaced Francois against Alabama, and he will start the next game, Fisher said. A three-star recruit, Blackman was the lower ranked of the two quarterbacks Florida State signed in its 2017 recruiting class. Four-star Bailey Hockman was ranked No. 180 in the ESPN 300. Another backup quarterback, J.J. Cosentino, attempted nine passes last season.
Francois, a native of Orlando, Florida, had a disappointing performance against Alabama's defense, completing 19 of 33 passes for 210 yards with 1 touchdown and 2 interceptions.
He was better last season, finishing with 3,350 passing yards with 20 touchdowns and 7 interceptions.
The Seminoles host Louisiana-Monroe in Tallahassee, Florida, this week and No. 18 Miami the following week.
ESPN's Mark Schlabach contributed to this report.