A university official familiar with the agreement told The Associated Press on Saturday that Stoops has agreed to join new Florida State coach Jimbo Fisher in early January after both schools bowl games.
The official spoke on condition of anonymity because neither Stoops or Fisher has signed new contracts yet.
Stoops, 42, is Arizonas defensive coordinator. He is the younger brother of Oklahoma coach Bob Stoops and Arizona coach Mike Stoops.
Mark Stoops inherits a Seminole defense that ranked 110th nationally in 2009, surrendering 444.3 yards and 30.8 points a game. He succeeds Mickey Andrews, who is retiring after 26 seasons as Florida States defensive coordinator.
Arizonas defense ranks 21st nationally, giving up 315 yards a game a game.
Stoops in not unfamiliar with Florida, having coached three seasons at Miami as secondary coach for the Hurricanes before joining brother Mike at Arizona in 2004.
Fisher, who is replacing Bobby Bowden, still has several positions to fill.
