ANZ Bank's monthly survey shows sentiment turned more gloomy with a net 45 percent of firms expecting the economy will deteriorate over the next year, up five points from June.
That was the highest level of unhappiness since May 2008.
The number expecting better times for their own businesses, which is regarded as a better indicator of economic activity, fell to a net 4 percent.
That was half the level the month before and the lowest since 2009.
ANZ chief economist Sharon Zollner said businesses didn't seem to be able to shake the blues they had suffered since the election.
"Firms are struggling with capacity constraints, cost increases, squeezed profitability. There's still stuff going on out there, but it's got a bit harder. You can add in to mix policy uncertainty around industrial relations, minimum wage increases and overseas investment," she said.
She said while there was economic support from government spending and overseas trade, there was also a danger the downbeat mood would become a self-fulfilling prophecy.