Lawson (12-2) knocked off Blair Oaks (12-2) 28-12 in the Class 2 semifinal game.
Prior to Saturday's contest, the Falcons had reeled off 12 consecutive wins with their only loss coming against Class 4 squad Moberly.
Lawson's defense held Blair Oaks in check for much of the afternoon. The Cardinals took a 6-0 lead into halftime on the first of Preston Smidt's three touchdowns on the day.
Smidt and quarterback Garret Titus each rushed for scores in the third quarter to extend the Cardinals lead to three possessions.
Blair Oaks found the end zone twice in the fourth quarter, but Lawson closed out its eighth straight win.
The victory isn't the Cardinals first signature win over the Falcons. Lawson beat Blair Oaks 38-17 in the 2007 state championship game. They'll try to duplicate those results against Lamar at 4:15pm Friday.