Afton Ringgenberg and Jill Johnson combined to score 37 of Rockwell City-Lytton's 46 points. Ringgenberg scored 19 while Johnson scored 18.
Treynor held an 11-9 advantage after the first quarter of play before the Wildcats outscored the Cardinals 14-7 in the second quarter to take a 23-18 halftime lead.
Rockwell City-Lytton took advantage of 18 Treynor turnovers while holding the Cardinals to 25 percent shooting. No Treynor player reached double figures.
Rockwell City-Lytton will attempt to win the Class 1A title for the second-straight year Friday at 7:00 p.m.
Treynor ends its season at 20-6.
Rockwell City-Lytton (26-1) 9 14 12 11 -- 46
Treynor (20-6) 11 7 2 11 -- 31