Top-seeded Bell City (23-5) will play No. 2 Delta (19-9) at 7:30 p.m. on Thursday in the district finals.
Johnson, who came into the game six points shy of 2,000, went the first nine minutes of the game without a point.
Even without their leading scorer on the board, the Cubs were able to jump ahead 23-6 early in the second quarter.
Bell City coach David Heeb praised Johnson's unselfish play and smart shot selection.
"He just takes the play that's given to him" Heeb said. "He's going to get you a good shot. He's a great player because he makes the players around him better."
Johnson and Bell City point guard Derek Pobst continued to feed the ball into the post early on.
Jeff Liggins and Tyler Victor combined for 12 of Bell City's 18 first-quarter points.
"They did a good job getting the ball inside to us," Victor said.
Bell City got its outside game going in the second quarter with the help of Zak McIntyre, who hit three 3-pointers in the quarter. Johnson scored six in the quarter to capture his 2,000th point.
"We didn't play very good last night, but we played better tonight," Victor said, referring to an 86-48 first-round win over Zalma.
"We played a good first half. Derek really did a good job of distributing."
The Cubs led 42-14 at halftime and kept rolling from there. Johnson flexed his scoring muscles in the third, scoring seven straight points for the Cubs and 13 for the quarter.
Johnson finished with a game-high 19 points.
Liggins added 17 points for Bell City.
"Jeffrey has a lot of talent, and he played hard tonight," Heeb said of Liggins. "When Jeffrey plays hard he's going to do well."
Delta, trailing 29-27 at halftime, outscored Oran 24-15 in the third quarter on its way to the district finals.
Daniel Cook led four Bobcats in double figures with 14 points. Derek Helderman added 12 and Cody Crowden and Brent Menz had 10 apiece.
Ryan Bouge led Oran (6-15) with 23 points, and Garrett Roslen scored 19.
POPLAR BLUFF - Fifth-seeded Meadow Heights upset No. 4 Ellington 71-56 in the Class 2 District 2 semifinals and will meet defending Class 2 state champion East Carter County on Thursday.
Brad Adams led the Panthers (15-11) with 21 points. Anthony Bollinger added 16, and Terry Wagner had 15.
No. 2 Advance moved on with a 68-47 win over Puxico. Tyler Bowman led the Hornets with 14 points, Drew Sherman had 13 and Daryl Wade scored 11.
Advance will face No. 6 Van Buren in Thursday's semifinals. Van Buren upset No. 3 South Iron County 54-45.