Chicago defender Evan Whitfield scored early in the first half and Justin Mapp struck early in the second.
Chicago improved to 8-0 all-time at home against Kansas City, outscoring the Wizards, 22-5. The Fire tied Kansas City for the top home mark in the MLS at 5-1-2.
Five minutes after coming up with a criticial defensive play to deny Igor Simutenkov, Whitfield scored as he capitalized on miscommunication between defender Nick Garcia and goalkeeper Tony Meola at the right corner of the penalty area.
Mapp put a long-range shot through Meola's hands in the 53rd minute and Zach Thornton recorded his fourth shutout as the Fire improved to 7