Mason County led 59-46 with 5:30 left and 70-60 with 1:02 to play, but struggled at the free throw line and Bracken County closed to within three at 71-68 with 20 seconds to go.
The Royals missed two free throws with 10 seconds left.
Austin Crawford, who scored a game-high 45 points for Bracken County, missed a three-point shot with 1.7 seconds left.
Sam Kumler sank two free throws to seal the victory.
Mason County was 13-of-23 from the free throw line in the fourth quarter.
Leevi Dunaway hit 10-of-13 free throws in the fourth quarter and 16-of-22 for the game. He had a double-double with 30 points and 10 rebounds.
Jaylen Lofton scored 16 points and Ty Fox added 14 points.
Dalton Perkins blocked five shots.
Crawford scored 22 of Bracken County's 25 fourth quarter points.
For the game, Crawford was 18-of-34 from the field (2-of-12 on three-pointers) and 7-of-12 from the free throw line. He had a game-high 11 rebounds.
MC (17-15) Dunaway 30, Kumler 6, Lofton 16, Perkins 2, Fox 14, Boyd 5
BC (16-14) Crawford 45, Engnes 5, Jones 4, Tad Fisher 6, Appleman 3, Deaton 2
MC 14 17 18 24- 73
BC 12 16 15 25- 68