The fire was reported about 2:25 a.m. in a first-floor storage unit near a kitchen at the stadium, located at 333 W. 35th St. It was out shortly after 3 a.m.
The firefighter was taken to Mercy Hospital and Medical Center with injuries that were not thought to be life-threatening, according to fire media.
Police say it is standard to call the Bomb and Arson Unit in for fires at high-profile locations.
The White Sox said at the time of the fire staff were present at the ballpark, which is staffed 24 hours, but that none was injured.
US Cellular Field fire 2:25 am, 1st flr, kitchen or office, 1 line fire, out at 3:01 am, 1 FF injury to Mercy, non-life threatening— Chicago Fire Media (@CFDMedia) April 8, 2016