The smaller but quicker Eagles (3-1) outplayed the Cavilers for the entire 32 minutes.
Pierce City caused 22 Thomas Jefferson turnovers which led to 16 fast break points.
The Eagles used an 11-0 run to open the third frame and build a 38-20 edge. Thomas Jefferson narrowed the gap to 40-28 to end the period but it wouldn't help.
Pierce City scored seven of the first nine points of the final frame and held on for the victory.
The Cavilers' 6'10" center Justin Brown led his team in scoring with 17 points.
Cody Fitchpatrick paced the Eagles' balanced scoring attack with 15 points. Kole Kelley chipped in 14 points. Cedric O'Hara added 13 points. Zach Hyde recorded 7 points. Colton Drollinger finished with 5 points, and Ryan Turner tallied 2 points.
In the semifinal, Pierce City fell to Crane 79-49.
The Eagles trailed 20-15 after the first period and 44-24 at halftime.
Zach Chastain led the Pirates in scoring with 19 points. Jordan Bowling added 17 points.
Scoring for the Eagles: Kelley, 13 points; Fitchpatrick, 12, Drollinger and Hyde 8 apiece; Colin Garner, 5; O'Hara, 2; and Eric Parrigon, 1.
Pierce City will be in action on Dec. 4 at Wheaton. Tipoff is set for 6 p.m.