Wednesday's data from the Australian Bureau of Statistics showed the economy grew 0.9 percent in the June quarter, from the March quarter when it expanded by a rapid 1.1 percent.
Gross domestic product (GDP) was 3.4 percent higher than a year earlier, ahead even of the 2.9 percent growth boasted by the United States.
It was the strongest result in almost six years and handily beat market forecasts of 2.8 percent thanks to upward revisions of previous quarters.
Investors reacted by driving up the local dollar up a quarter of U.S. cent to $0.7215.
"It's a pretty good print for the quarter and with the upward revisions," said Su-Lin Ong, chief economist at RBC Capital Markets.
"The composition is encouraging as well. We've seen pretty decent domestic demand and reasonably broad-based growth."
The ruling Liberal-National coalition will be hoping the news distracts voters from the endless internecine warfare that saw Prime Minister Malcolm Turnbull ousted last month and replaced with former Treasurer Scott Morrison.
This was the fifth change of prime minister in eight years and sent the government crashing in opinion polls. An election is due by May next year but risks are for an earlier vote.
Analysts fear the political dysfunction could take a toll on consumer sentiment, just as spending seemed to be making a comeback. Household consumption had rebounded in the June quarter to add 0.4 percentage points to GDP.
Also adding to growth were net exports, home building and government spending.