Le Plateau-Mont-Royal (French pronunciation: [lə plato mɔ̃ ʁwajal]) is a borough (arrondissement) of the city of Montreal, Quebec, Canada.

The borough takes its name from its location on a plateau, on the eastern side of Mount Royal and overlooking downtown Montreal, across its southern border. The borough is bordered to the south by Sherbrooke Street, to the north and north-east by the Canadian Pacific Railway tracks, and to the west by Hutchison (north of Mount Royal Avenue), Park Avenue (between Mount Royal and Pine Avenue) and University Street (south of Pine Avenue). It is one of the most densely populated boroughs in Canada, with 105,813 people living in an 8.1 square kilometre (3¼ sq. mi.) area.

There is a difference between the borough named Plateau-Mont-Royal (which is a political division of the City of Montreal) and the neighbourhood referred to as the Plateau. The borough includes not only the Plateau neighbourhood itself, but also the neighbourhoods of Mile End (bounded by Avenue du Mont-Royal to the south and the Avenue Henri-Julien to the east) and Milton Park (bounded by University, Sherbrooke, Saint-Laurent and Pine). The latter two neighbourhoods are generally considered to be distinct from the Plateau neighbourhood.

The Plateau is famous for being a major centre for the arts, with a large concentration of artists, musicians and creative organizations. Many artistic institutions are established in the Plateau, including the National Theatre School of Canada, the Quebec Conservatory of Music in Montreal, Les Grands Ballets Canadiens and many theatres (such as le Rideau vert, le Théâtre de Quat'Sous, La Licorne and le Théâtre d'Aujourd'hui). The Plateau has many parks, including Jeanne-Mance park, La Fontaine park, Sir-Wilfrid-Laurier park, Saint-Louis Square and Gérald-Godin plaza. Mount Royal Park is also accessible from the Plateau-Mont-Royal.

Due to its large concentration of French immigrants who arrived in the early twenty first century, the neighbourhood has been named the "French District", "Le Petit Paris", "La Petite-France", or ironically "La Nouvelle-France".

Starting in 1745, the urbanized area of Montreal began to extend beyond its fortifications. The Plateau-Mont-Royal was born when the Faubourg Saint-Laurent to the north became the main area of development. In 1792, Montreal expanded, with new official limits about two kilometres (1¼ miles) beyond the original fortifications. Mount Royal and Duluth Street formed its new boundaries. Farther from the centre, especially to the west, English-speaking families of the era owned large houses surrounded by gardens, and the Religious Hospitallers of St. Joseph owned a large field which would later become the site of the future Hôtel-Dieu. Even further from the city were large country estates whose farms were owned by the Montreal bourgeoisie.

In 1850, a reservoir was installed in what is today the location of Saint-Louis Square. Its function was to supply water to Côte-à-Baron residents, who lived on the downward slope below Sherbrooke Street. At that time, a farm on the site of the current La Fontaine Park was converted into grounds for military exercises. To the north, other cities were formed following new economic activity, giving rise to the village of Coteau-Saint-Louis in 1846. A chapel was built two years later, then replaced in 1857 by the Church of Saint-Enfant-Jésus du Mile-End. Nowadays, the Mile End is a neighbourhood adjacent to the Plateau-Mont-Royal borough, but it was only in 1878 that the village of Saint-Louis-du-Mile-End was born. By the end of the century, the mountain was purchased by the City of Montreal and developed into Mount Royal Park. La Fontaine Park took the place of the military field and the reservoir Côte-à-Baron became the Saint-Louis Square.

The village of Saint-Jean-Baptiste took shape circa 1861. Its central point was also the location of its market (the first market was built in 1870 and replaced by a more modern market in 1933, which was demolished in 1966). The civic centre was located at the intersection of Saint Lawrence Street (later Saint Laurent Boulevard) and Rachel Street. The villages of Coteau-Saint-Louis and Saint-Jean-Baptiste merged into Montreal in 1893 and 1886 respectively. As for Saint-Louis-du-Mile-End and DeLorimier, they would be annexed to Montreal in 1910 and 1909 respectively. At that time, the population of Montreal spilled over east of Papineau Road (today Papineau Avenue), where elegant houses and avenues were located.