Whyalla is a city and port located on the east coast of the Eyre Penisula opposite Port Pirie in South Australia. Population (2001) 22,836.

It was founded as Hummock Hill in 1901 by the Broken Hill Proprietary Company, Ltd (BHP) as the end of a tramway bringing iron ore from the Middleback Ranges to be used in the lead smelters at Port Pirie as flux. A jetty was built to transfer the ore. The settlement consisted of small cottages and tents clustered around the base of the hill. The arid environment and lack of natural fresh water resources made it necessary to import water in barges from Port Pirie.

On the 16th of April 1920 the town was proclaimed as Whyalla. The ore conveyor on the jetty was improved and ore began to be shipped to the newly built Newcastle steelworks. The town grew slowly until 1938.

The BHP Indenture Act was proclaimed in 1937 and provided the impetus for the construction of a blast furnace and harbour. In 1939 the blast furnace and harbour began to be constructed and a commitment for a pipeline from the Murray River was made. A shipyard was built to provide ships for the Royal Australian Navy. The population began rising dramatically and many new facilities, including a hospital and abbatoirs, were built.

In 1941 the first ship from the new shipyard, the HMAS Whyalla was launched and the blast furnace became operational. By 1943 the population was more than 5,000. On the 31st of March the Murray River pipeline from Morgan became operational. In 1945 the city came under combined company and public administration and the shipyard began producing commercial ships. In 1948 displaced persons began arriving from Europe.

In 1958 the Company decided to build an integrated steelworks at Whyalla. They were completed in 1965. In the following year salt began to be harvested and coke ovens were built. The population grew extremely rapidly, and the South Australian housing trust was building 500 houses a year to cope with the demand. Planning for a city of 100,000 was done by the Department of Lands. A second pipeline from Morgan was built to cope with the demand.

In 1970 the city adopted full local government status. The shipbuilding slump resulted in the closing of the shipyards, which were at the time the largest in Australia, in 1978. From a peak population of 33,000 in 1976, the population dropped rapidly. Since then the city has gone through a slump. The 2001 census population of 22,836 meant that for the first time in more than 40 years Mount Gambier, with a population of 23,282, is South Australia's second largest city.

The BHP long products division was divested in 2000 to form OneSteel. The Whyalla steelworks is the sole producer of rail and steel sleepers in Australia.

HMAS Whyalla was landlocked as a tourist attraction in 1987. In the late 1990s the spectacular annual migration of the Australian Giant Cuttlefish Sepia apama to the reef areas north of Whyalla around Black Point and Point Lowly became recognised by international divers. The Whyalla Conservation Park provides an example of the natural semi-arid environment.