Emergency services were reportedly called to Wool Road in Dobcross at around 7pm.
Greater Manchester Police have confirmed that a woman was rescued from the canal, but she later died despite efforts to save her.
A Greater Manchester Police spokesman confirmed: "At 7pm last night (Monday 18 November) we were called to reports of concern for welfare of a woman in the canal on Wool Road, Dobcross.
“Emergency services attended, and sadly, despite the best efforts of those at the scene, she was pronounced deceased.
"A scene remains in place whilst we conduct enquiries, and we advise members of the public to avoid the area.”
A Greater Manchester Fire and Rescue Service spokesperson added: "At around 7.05pm on Monday, two fire engines from Oldham and Stalybridge fire stations were called to an incident on Wool Road, Oldham.
"Crews quickly arrived at the scene and liaised with Greater Manchester Police to administer trauma care to one person rescued from the water, before they were passed into the care of North West Ambulance Service.
"Crews were in attendance for roughly one hour."
