Montereau-Fault-Yonne (French pronunciation: [mɔ̃tʁo fot‿jɔn] ⓘ, before 1992: Montereau-Faut-Yonne),[3] or simply Montereau, is a commune in the Seine-et-Marne department in the Île-de-France region in north-central France.

Montereau-Fault-Yonne straddles the confluence of the rivers Yonne and Seine at the far south-east of the Île-de-France region, 70 km southeast of its administrative centre, Paris.

The old town centre is located in ville basse while Surville is an assembly of high rise buildings, erected after World War II, and is in many ways a typical cité in the Île-de-France.

The old château-park in Surville (now the site of a high school Lycée André Malraux) however gives a very nice view over the confluent and the Seine-et-Marne region.

John the Fearless was killed on the town's bridge in September, 1419 by Tanneguy du Chastel and the sire de Barbazan, during a conference with the dauphin (who became in 1422 Charles VII).

In January 2012, the mayor proposed development of Napoleon's Bivouac, a commemorative theme park at a projected cost of 200 million euros.