Harry Kane scored after just three minutes for Tottenham, while Aaron Lennon's persistence led to a second goal in the 84th minute as Mauricio Pochettino's team ended its trip to the USA with two wins and a draw from three games.
But although the result was positive, it looks like Pochettino still has work to do, as Tottenham barely got out of second gear throughout the match at Toyota Park.
Kane handed the visitors an ideal start in Chicago, striking early thanks to fine lead-up work from Lewis Holtby, who stole the ball from the Fire's Jeff Larentowicz before teeing up his 20-year-old teammate.
The rest of the game was rather pedestrian but Tottenham wrapped up the victory with six minutes remaining, as Lennon beat Bakary Soumare and the Fire's reserve goalkeeper Kyle Reynish to a bouncing long ball, before tapping into an empty net.
Chicago's coach Frank Yallop would have been furious with his team's start, as it gave up possession on the edge of their penalty area in just the fourth minute, allowing Kane to score.
But the Fire worked their way back into the contest as the half wore on with Matt Watson testing Tottenham keeper Brad Friedel in the 25th minute.
As the clock ticked past the half-hour mark, Tottenham midfielder Erik Lamela continued his strong preseason, skipping past a couple of opponents before forcing Chicago goalkeeper Sean Johnson into a fine save.
Lamela, who scored twice in a 3-2 win over Toronto FC on Wednesday, was at it again four minutes later, surging through midfield before a flying Johnson again kept the Argentine's shot from finishing in the net.
The hosts looked more comfortable after halftime, taking advantage of a number of substitutions from Pochettino, although Chicago struggled to fashion genuine goalscoring chances in the first 20 minutes of the second period.
In the 69th minute, the Fire's Dilly Duka linked up with a couple of teammates to work his way through Tottenham's midfield before his shot was saved lowdown by Friedel, while Chicago striker Matthew Fondy got into the box with 15 minutes left only to have his shot blocked.
Tottenham finished the match stronger with Lennon doubling the lead before Christian Eriksen got in behind the Fire's defence only for Reynish to smother his shot on the edge of the area.