Downriver is a region of the Detroit metropolitan area in the U.S. state of Michigan covering 18 municipalities in Wayne County, south of Detroit, along the western shore of the Detroit River.

The name derives from the fact that the Detroit River, after running more or less west along the banks of Detroit and Windsor, Ontario, then bends to flow largely south before emptying into Lake Erie. Communities to the south of the city can thus be accessed by traveling downriver (as opposed to upriver) along the waterway.

The Downriver label can be controversial, and many communities and the businesses therein have made various attempts to embrace, reject, or redefine the Downriver name.

The proximity to Canada across the Detroit River, coupled with residents associated with The Purple Gang, made Downriver one of the nation's major bootlegging hubs during Prohibition. According to Intemperance: The Lost War Against Liquor by Larry Englemann, "Soon after the passage of prohibition thousands of residents of the downriver communities began participating in rum-running and consequently reaped nearly unbelievable riches from their activities. During the prohibition years, in Ecorse and the other downriver towns, crime paid. Lavishly."

In the first half of the 20th century, the urban communities in the northern and middle parts of Downriver were mainly populated by workers who were employed by the dozens of auto factories, manufacturing suppliers, ship builders, steel mills and chemical plants making up local heavy industry, including the Ford Rouge Plant Complex, Great Lakes Steel, McLouth Steel, and BASF.

While heavy industry is still an important source of jobs, since the late 20th century and industrial restructuring, these communities have a higher proportion of white collar workers, as the economy of Metropolitan Detroit has diversified. Newer developments have featured larger single-family houses for contemporary tastes, and improved freeways have made commuting longer distances feasible.

Brownstown Township, Flat Rock, Gibraltar, Huron Township and Rockwood in the southern parts of Downriver were predominantly rural communities during the first half of the 20th century. While these communities have been developed for residential use and had significant population growth and suburbanization since the late 20th century, some working farms can still be found in these towns.

Today, Downriver overall is known largely as a suburban Detroit region with working-class residential neighborhoods and recreational opportunities focused on boating, fishing, bird watching and waterfowl hunting areas around the Detroit River. The Detroit River International Wildlife Refuge, and an extensive network of recreational trails built under the Downriver Linked Greenways Initiative, are two environmental conservation and recreation projects in the region.