The suburb now known as Westminster came about at the request of residents who in 1994 requested the City of Stirling to rename the southern portion of Balga to Westminster after the name of the original estate in the area.
Between 1936 and 1955 a limestone road named Westminster Boulevard passed through the suburbs then known as Nollamara and Westminster Estate. Westminster Estate was subdivided prior to World War II, though development of the area remained limited up to the late 1940s because the area was perceived to be relatively isolated.
Most of the land at that time was used for market gardening and poultry farms. Due to the area's extensive jarrah and Banksia woodlands, timber cutting was also popular in the earlier days of the colony.
The Westminster area was resumed, along with the surrounding suburbs, by the State Housing Commission in the early 1950s to form the basis for the Mirrabooka Regional Centre, and Westminster was developed to capacity by 1970.