In 1958, Lot 223 was purchased and subdivided the following year. Four applications to build were approved in March 1959 and a major sale on 10 June saw nearly 300 blocks purchased. The subdivision was extended northwards in the early 1960s and Quinns Rocks was declared a townsite under the Local Government Act on 27 July 1962. Further extensions took place in 1964 and 1972. The locality encompassing this local government townsite, gazetted as "Quinns" in 1974 for future postal services, was changed to Quinns Rocks in 1977, so as to coincide with the townsite name.