The body was discovered at 8:30 a.m. Thursday morning, a short distance from the water's edge.
The Chicago Police Department's Marine Unit was initially called to the scene after a woman reported seeing a body floating in the water.
The body was then recovered from the water, officials said.
Evans,25, was last seen early Sunday morning just a half a mile away from the harbor.
Evans, an MBA student at Loyola University, was attending pride events with his friends during the weekend. Friends say they last saw him at a bar on the 3300 block of North Halsted.
Loyola University police were also on scene at Belmont Harbor Thursday morning, but they would not confirm if the body was Evans.
Chuck Brooks, a boater, was nearby as the scene unfolded.
"I saw something unusual but I didn't know what it was. . . Then we figured out it was probably a body," said Brooks.
The discovery of the body has dampened Fourth of July celebrations for some.
"Very disturbing that right near a very pleasant site is a place where somebody's life ended," said Ken Walker, passerby.
Meanwhile, police are calling it a death investigation. The medical examiner is expected to perform an autopsy to determine the cause of death and identify the body.