York St John University student Megan Roberts, from Wetherby, West Yorkshire, disappeared during a night out with friends in the city in January.
It was feared she became separated from friends and fell into the River Ouse near York's Lendal Bridge.
The woman's body was spotted by a member of the public at 3.30pm yesterday near a pub at Acaster Malbis, a village almost five miles south of York, police said.
Ms Roberts' family has been told of the discovery, although the body has not been formally identified.
A spokesman for North Yorkshire Police said: "The body of a woman has been found in the River Ouse at Acaster Malbis near to the Ship Inn.
"Police received a call at 3.27pm on Sunday 2 March 2014 from a member of the public who was walking in the area.
"Formal identification has not yet been completed, therefore we cannot confirm the identity of the deceased at this stage. The family of Megan Roberts have been informed of the discovery."
Ms Roberts vanished on January 23 after an evening out with friends.
The student was last seen on CCTV on the corner of Rougier Street and Lendal Bridge at around 2.20am.
Police believed the most likely explanation for her disappearance was that she got separated from her friends while under the influence of alcohol and fell into the Ouse near the bridge.
A week later Ms Roberts' mother, Jackie Roberts, said she believed the disappearance of her "beautiful daughter" appeared to be the result of "a tragic run of events with no one to blame".
Police divers searched the Ouse and officers used sonar equipment to scan the water from Lendal Bridge downstream to Naburn, but with no success.