Molina scored three times and the Cardinals banged out 19 hits to finish a 7-2 homestand and remain tied with Pittsburgh atop the National League Central.
Shelby Miller (14-9) earned the victory, allowing two runs (one earned) on three hits through five innings. He walked two and struck out one.
Seattle starter Erasmo Ramirez (5-2) was lit up five runs and eight hits, lasting just four innings.
Abraham Almonte and Franklin Gutierrez each drove in a run for Seattle.