Police said the marine unit responded to the 4900-block of South Lake Shore Drive, near the Hyde Park neighborhood, just before 8 p.m.
There, crews removed the person, who police say is a male of an unknown age, from the water.
A Chicago Fire Department spokesperson said the person was transported to a local hospital in critical condition.
Chicago police later confirmed that the person died at the University of Chicago Medical Center.
How he ended up in the water was not immediately clear. Area Two detectives are investigating.
Authorities did not immediately provide further information.