Heading into the midweek clash, New York had failed to win any of its past six matches following three defeats and as many losses.
New York returned to form and secured a post-season spot for the third consecutive year thanks to Alexander Ring and David Villa at Yankee Stadium, dousing Fire from the play-off race in the process.
After a goalless and uneventful first half, Ring broke the deadlock within two minutes of the restart – the Finnish midfielder capping a fine team move, having been teed up by Villa.
Villa went from provider to goalscorer four minutes later when the former Barcelona forward met Maximiliano Moralez's cut-back.
New York City is third in the Eastern Conference and 10 points adrift of Supporters' Shield leader Atlanta United, while Fire 12 points outside of the play-off positions.