Greenfield Park is a former city in southwestern Quebec, Canada. It is currently a borough of the city of Longueuil. It covers an area of 4.78 square kilometres (1.85 sq mi), with a population of 16,733 at the 2016 census of Canada. Greenfield Park is the only borough of Longueuil that has an officially bilingual status. It is primarily a post-WWI suburban area. Like the other two boroughs, most of the buildings in Greenfield Park are single-family homes. Nearly all of the land in Greenfield Park is built on, making it Longueuil's most densely populated borough.

Greenfield Park is divided into two sections. The older section of the borough is to the west of Taschereau Boulevard near Saint-Lambert, LeMoyne and Brossard, while the newer section is to the east, near the Saint-Hubert borough. Most of the Greenfield Park's businesses are located along Taschereau Boulevard, the south shore's most important commercial artery. The Charles LeMoyne Hospital, located on the Taschereau Boulevard, is the largest on the south shore.

Before becoming a town, the area known as Greenfield Park was land belonging to the Seigneury of Longueuil. It had been an agricultural area up until the end of the 19th century. Greenfield Park benefited from its proximity to neighbouring St. Lambert's rail line connected to the newly constructed Victoria Bridge, which was the only major rail link between Montreal and the South Shore. At the time, the bridge was the longest railway bridge in the world. Development had begun to spread into Greenfield Park, which merited the establishment of a town to provide services for the population.

Greenfield Park was named after the area's primary geographical features, which were in fact green fields and forests. The town was established on March 24, 1911. The original Charter of Greenfield Park gave reasoning for the town's creation:

Whereas the rate-payers of the territory comprised in cadastral lots Nos . 225 to 244 of the parish of Longueuil have by a large majority in number and value represented that, in consequence of the rapid increase of population within the said territory being a suburb of the city of Montreal and in consequence of the necessity for local improvements similar to those of other suburbs of Montreal, it is necessary that the said territory be created into a separate municipality and they have prayed, that the general principles of the Cities and Towns' Act be applied to the said municipality and also that they be granted several powers similar to those of other suburbs of Montreal which are not contained in said act . . .

With the creation of the town came to need to put infrastructure and services in place. The only way for citizens to reach nearby Montreal was by rail, through the Grand Trunk Railway or the Montreal and Southern Counties Railway. In 1913, Greenfield Park, along with neighbouring municipalities St. Lambert, Montreal South and Longueuil, built a shared sewer system and water filtration plant. The town also used artesian wells as a source for drinking water.

During World War I, such a high percentage of Greenfield Parkers served in the Canadian forces that regular town meetings could not be held.^{[citation needed]} Similarly, in World War II, Greenfield Park was the Canadian community that had one of the highest participation rate of military volunteers for its size. This fact was recognized by both Prime Minister William Lyon Mackenzie King and the Minister of National Defence, J.L. Ralston.

Following the war, returning veterans were able to purchase homes with financial assistance through a purchasing program put into place by the town.^{[citation needed]}