The Bulldogs (28-2) led 34-30 at halftime and then 58-48 heading into the final quarter before holding off a late Hawks charge.
Myrtle (21-16) pulled to within five points with four minutes left when McAdams' Marquita Phillips hit a 3-pointer. Seconds later, Gilmore got a steal and fed it to Phillips for an easy layup to extend the lead again.
Aspriona Gilbert scored 37 points for Myrtle, which won the Class 1A title in 2003.
McAdams girls won their third state title.