The Kansas City unbeaten streak reached nine games and it moved 5 points in front of Chicago for the lead in the Eastern Conference. Chicago had won seven of its previous eight games.
Kei Kamara set up Zusi's first goal in the 11th minute, sending a low cross just outside the penalty area. Zusi turned on the ball and put a first-timer past goalkeeper Sean Johnson.
Zusi also scored on a breakaway in second-half stoppage time.