Police and the SCDF were alerted at about 7am, after a passerby saw what looked like a body floating in the water.
The aunty was wearing a red checked shirt, and officers pronounced her dead at the scene.
The passerby had spotted the body at the Kallang River stretch along Bendemeer Road.
One eyewitness at scene said that the area, where many elderly Singaporeans live, has seen 2 suicides in recent months.
This case has been classified as one of unnatural death and police investigations are in progress.