Morris sprained his left ankle last week in Miami's loss to North Carolina, and was listed as doubtful on the team's injury report as recently as Thursday.
The Hurricanes announced the decision to have Morris start over Ryan Williams with about 10 minutes remaining until kickoff against the Seminoles. Earlier in the week, Miami coach Al Golden said Morris would only start if the coaching staff deemed he was completely ready to play.
Morris arrived at the stadium about two hours before kickoff with a walking boot protecting his ankle. He went through two warmups on the field pregame, with Golden and offensive coordinator Jedd Fisch seeming to keep watchful eyes on much of his work.
"He just felt progressively better as the week went on," Golden told ABC in a televised interview just before kickoff.
Golden also said Williams is ready if needed.
Morris enters the game having thrown for 1,991 yards this season, including a school- and Atlantic Coast Conference-record 566 yards against North Carolina State.