Stills' TD reception capped an eight-play, 83-yard drive, breaking a 13-13 tie.
It came after the Seminoles (2-1) had tied the score on the previous possession when backup quarterback Clint Trickett found Rashad Greene for a 56-yard touchdown strike.
Jimmy Stevens' field goal with 2:05 left iced the victory for the Sooners (2-0).
Jones went 18-of-27 passing for 198 yards and two interceptions, and Stills made six catches for 87 yards as Oklahoma defeated the Seminoles for the second straight year.
Starting FSU signal-caller E.J. Manuel, who sustained a bruised left shoulder in the second half, completed 13-of-19 passes with two interceptions. He also ran for 49 yards.