Prince Alfred Square is a 1.5-hectare (3.7-acre) park on the northern side of the Parramatta River in the central business district of Parramatta. It is one of the oldest public parks in New South Wales and is listed on the New South Wales State Heritage Register. St Patrick's Cathedral is located directly opposite the square to the west.

The park site was the site of Parramatta's second gaol (1804–1841) and first female factory (1804–1821). Prisoners were transferred to the new Parramatta Gaol upon opening in 1842 and the gaol was subsequently demolished. It was authorised as a 'village green' for the people of Parramatta by Governor Bourke on 27 November 1837, and was referred to as the old Gaol Green or Hanging Green by local townspeople. A perimeter fence was subsequently erected and games such as cricket were played.

The oldest plantings in the park include Moreton Bay figs, a camphor laurel and a Bunya pine that date from the mid Victorian period (c.1869–70s). It was named 'Alfred Square' in 1868 to commemorate the visit of Prince Alfred, Australia's first Royal visitor, during which he visited Parramatta.

It was added to the New South Wales State Heritage Register on 28 August 2017.

Aboriginal people have occupied the Parramatta region for tens of thousands of years. Evidence of their occupation can be found in the form of rock shelters with deposits, open campsites, middens, axe-grinding groove sites, scarred trees, hand stencils and drawings. In pre-colonial times, Parramatta would have been very attractive to Aboriginal people as the landscape would have supported a wide variety of plant and animal life. The City of Parramatta is located on Parramatta River at what is effectively the head of Sydney Harbour. Permanent fresh water was available in the river upstream of the tidal limit and fresh water would also have been available from creeks and surface waterholes, in more clayey parts of the sand terrace. Aboriginal people living in this location would have had access to freshwater and saltwater food resources such as: ducks, eels, shellfish, crayfish, fish and turtles. Terrestrial resources in the Parramatta area included woodland and grassland mammals such as: kangaroos, possums and flying foxes. The grassy woodlands would also have provided access to smaller animals and insects and to native fruits, berries, seeds, yams and roots.

Parramatta CBD, at the time of European settlement, is thought to have been the territorial lands of the Burramattagal (also spelt Boromedegal, Boora me di-gal, Booramedegal and Burramedigal). The Burramattagal appear to have belonged to a larger cultural group that extended across western Sydney, although exact language group affilitations of pre-contact groups in the Parramatta region is open to some debate. Much of our knowledge about the traditional life style of Aboriginal people living in the Parramatta CBD area is reliant on archaeological investigation, as the Burramatta People (as a distinct population group) disappeared very soon after European settlement of the area.

European settlers, attracted to Parramatta for its fertile soils and its suitability for water transport, began arriving in the region in the late 18th Century. Parramatta quickly became the focus of residential, commercial and industrial development. The establishment of the town of Parramatta and cultivation of the surrounding land, would have resulted in many Aboriginal sites being disturbed or destroyed without being recorded. To date only a relatively few Aboriginal sites have been recorded in the Parramatta local government area.

It is believed the site of Prince Alfred Square was a Burramatta women's site.