Swanston Street is a major thoroughfare in the Melbourne central business district, Victoria, Australia. It was laid out in 1837 as part of the original Hoddle Grid. The street vertically bisects Melbourne's city centre and is famous as the world's busiest tram corridor, for its heritage buildings and as a shopping strip.

Swanston Street runs roughly north–south in-between Russell Street to the east and Elizabeth Street to the west. To the south it becomes St Kilda Road after the intersection with Flinders Street, whilst the road's northern end is in the suburb of Carlton at Melbourne Cemetery. This northern section was originally named Madeline Street. The street is named after merchant, banker and politician Charles Swanston.

Swanston Street was one of the main north–south streets originally laid out as part of the 1837 Hoddle Grid. Originally carrying pedestrians and horse-drawn traffic, the street resembled many typical European avenues of the 19th century. By the end of the 19th century it also accommodated one of the major tram lines through the city. With the advent of the automobile in the early 20th century, the street became a major thoroughfare, carrying car traffic between areas north of the city and St Kilda Road throughout most of the 20th century.

In the latter half of the 20th century, the southern half of the street had problems with heavy traffic and its associated pollution, homelessness, loitering, and a plethora of discount stores, fast food outlets, sex shops and strip joints.

As part of Victoria's 150th birthday celebrations, Swanston Street was closed to traffic, turfed and treed between Flinders Street and Lonsdale Street for a Summer street-party on February 9-10, 1985. The conversation then began around the permanent transformation of Swanston Street. In March 1992, the street was closed to daytime private through-traffic between Flinders and La Trobe Streets, roughly half its length. This section is known as Swanston Street Walk. Swanston Street was redeveloped in 1992 with a number of public sculptures being established through the Percent for Art Program. The most famous of these statues is of a small bronze dog called Larry La Trobe by Melbourne artist, Pamela Irving. By the turn of the 21st century, the street carried nine tram routes, with the frequency of trams being the highest in Melbourne.

In November 2008, the newly elected Lord Mayor of Melbourne Robert Doyle proposed returning private vehicle traffic to the street. The move attracted opposition from the Public Transport Users Association, Australian Greens and Bicycle Victoria. The idea was rejected and, by January 2010, plans to make the entire length of Swanston Street in the city car-free were announced by the Lord Mayor himself, a complete reversal of his previous stance.

Many marches, rallies and protests involve the use of Swanston Street, resulting in planned and unplanned road closures. The street is the venue for many annual events, including the Moomba parade, the AFL Grand Final parade and Melbourne Cup parade. It is also the major route for the Anzac Day parade because Swanston Street leads into St Kilda Road, the site of the Shrine of Remembrance.

Swanston Street was one of the busiest roads in Melbourne, carrying a large volume of private car traffic, mostly transiting through the city. In 1992, the street was made partially car-free, with limited exemptions for small freight, buses and private cars during certain times of the day. After that, proposals for the street to become entirely car-free gained momentum.