The body was found around 1:53 p.m. in the North Branch Chicago River near River Park in the 3000 block of West Argyle Street, Chicago police said.
The deceased person is a male whose age was not yet known, police said. He was found unresponsive in the water and was pronounced dead at the scene.
The person has not yet been identified.
No further information was immediately available as Chicago police continue to investigate the death.