The body was spotted in the river about 8:10 a.m., said Jose Estrada, a police spokesman.
A police boat was investigating at the scene near the 4200 block of West Foster Avenue Tuesday morning, Estrada said.
The body was later identified as that of Robbie Garrett, 40, of the 10900 block of West Racine Avenue, by the Cook County Medical Examiner's Office.
Garrett was pronounced dead on the scene at 8:20 a.m., according to the medical examiner's office.
No further information was immediately available.