Kim Geyer and Crystal Wallace, up from the JV team, scored 15 points to lead Whitmire.
Shardae Lynn had 17 points and Lakesia Roseboro had 14 for Great Falls (14-10).
The Lady Red Devils led 22-11 at the half and 38-25 going into the fourth quarter. WHS cut the lead to 10, 47-37, with 1:53 left, but could get no closer.
Great Falls will face Hunter-Kinard-Tyler or McCormick on Tuesday in the third round of the playoffs.
Whitmire finishes its season at 15-6.
Great Falls 54, Whitmire 43
WHS 4 7 14 18 - 43
GF 8 14 16 16 - 54
Notes: The playoff game was moved from Friday to Thursday due to a Beta Club event ... Geyer has been named all-region player of the year and to both all-state and all-region teams ... Jocelyn Hopp also made the all-region team.
DUE WEST - Dixie eliminated Whitmire's varsity boys' basketball team 71-49 on Wednesday in the first round of the Class A state playoffs.
Desmond Harp led the Wolverines with 19 points and David Reed added 16.
Whitmire finishes its season at 6-18.
UCHS YELLOW JACKETS
Dwight Brannon broke the 1,000-point barrier, with 1,026 points for his career. Brannon and Devin Booker were both named all-region performers.