On the goal, Austin Berry's header found a streaking Larentowicz, who headed the ball into the net from 5 yards out, recording his initial goal for Chicago.
The Fire improved to 2-4-1 with the result.
Andy Gruenebaum made six saves for the Crew (2-2-3), who lost for the first time in four games.
Costly malfunction causes beer flood at Boston-area brewery
Megyn Kelly: Santa Claus and Jesus are both white men