The Fire (3-7-15) hadn’t won an MLS match since June 12. They had gone 0-3-7 since then, setting the league record for ties in a season with 15 in its last match.
With the three points for the victory, Chicago climbed into seventh place in the Eastern Conference, moving past Toronto and New England.
Chicago made it 2-0 when Gargan, who was traded from Toronto on July 28, headed Pavel Pardo’s deflected corner kick by Kocic and a pair of Toronto defenders in the 69th minute.
Fire goalkeeper Sean Johnson made three saves in his fifth shutout of the season.