Harbourfront is a neighbourhood on the northern shore of Lake Ontario within downtown Toronto, Ontario, Canada. Part of the Toronto waterfront, Harbourfront extends from Bathurst Street in the west, along Queens Quay, with its ill-defined eastern boundary being either Yonge Street or York Street. Its northern boundary is the Gardiner Expressway. Much of the district was former water lots filled in during the early 1900s to create a larger harbour district. After shipping patterns changed and the use of the Toronto Harbour declined, the area was converted from industrial uses to a mixed-use district that is mostly residential and leisure.

Toronto's harbour has been used since the founding of Toronto for shipping and industrial purposes. The Town of York was founded to the west of the Don River, along the waterfront. When the town was founded, the water's edge was approximately where today's Front Street is located. Over time, the area south of Front Street to today's water's edge south of Queen's Quay was filled in with landfill, creating piers and area for industrial development.

Prior to the 1972 federal election, Prime Minister Pierre Trudeau announced the Harbourfront project, which would expropriate the industrial port lands from York Street west to Bathurst Street, south of Queen's Quay and convert them to a cultural and residential district for Toronto, similar to the Granville Island district in Vancouver. The federal government has converted the industrial area to an area mixed with art galleries, performance spaces, boating areas and parks. The surrounding neighbourhood, formerly industrial has been converted by private land developers into a series of condominium towers overlooking the project and Lake Ontario.

From its beginnings as Harbourfront Corporation, a federal Crown Corporation established in 1972, Harbourfront Centre was formed on January 1, 1991, as a non-profit charitable organization with a mandate to organize and present public events and to operate a 4.0 ha (10 acres) site encompassing York Quay and John Quay (south of Queens Quay West). Since its inception, Harbourfront Centre has been used by artists whose work would not normally be seen in commercial venues in an effort to foster new forms of arts and expression.

In July 2012, Waterfront Toronto began a major reconstruction of Queen's Quay West, requiring the 509 streetcar to be replaced with buses for the duration of the construction. On October 12, 2014, streetcar service resumed on 509 Harbourfront route after an absence of over two years in order to rebuild the street to a new design. With the new street design, two auto lanes south of the Toronto Transit Commission's (TTC) streetcar tracks were eliminated between Spadina Avenue and York Street in order to extend Harbourfront parkland to the edge of the streetcar tracks. The Martin Goodman Trail (a bicycle path), two rows of trees, benches and a wider pedestrian space are located on the immediate south side of the streetcar tracks.

The area along the waterfront is composed of mixed uses. The federal government lands to the south of Queen's Quay include a community centre, a Toronto Fire Services station, various boating uses, parkland and the Harbourfront Centre. To the north of Queen's Quay, all of the industrial lands along the street have been replaced with high-rise condominium towers. To the east of the federal government lands, the waterfront is mixed with industrial uses, a hotel, ferry docks, boating uses, a sugar factory and vacant lands.

The neighbourhood is separated from the rest of downtown Toronto by the elevated Gardiner Expressway. A project to link Lower Simcoe with Simcoe Street via tunnel was completed to provide a new link between Harbourfront and downtown, though access between the waterfront and the core remains an issue. Proposals have been made to demolish the expressway in the area. One proposal was to demolish the highway east of Spadina Avenue. Another proposal, to demolish the highway from the Don River to Jarvis Street, is being actively studied by the City of Toronto.^[when?]

Billy Bishop Toronto City Airport, also known as Toronto Island Airport, presents other neighbourhood issues. The airport, located to the southwest of the neighbourhood, is opposed by local community groups and some city politicians, including Toronto's past mayor, David Miller, as an impediment to the redevelopment of the waterfront lands. Another former mayor of Toronto, Rob Ford, backed an expansion of the airport, as it created jobs. The airport, built in the 1930s, is utilized for regional air travel. The airport generates hundreds of noise complaints monthly to its operator, the Toronto Port Authority, now PortsToronto. The Toronto Port Authority confirmed on September 12, 2008, that Porter Airlines was fined for breaking noise curfews in its operations at the airport. In 2008, a study by the Port Authority was conducted seeking ways to reduce noise from Porter's takeoffs and landings.