March's ANZ-Roy Morgan Consumer Confidence index fell sharply into negative territory at 91.3 points, well below last month's 101.1 points.
Any score under 100 indicates pessimism.
The impact of the Middle Eastern conflict on consumers was immediate, with every metric in the latest survey turning negative.
ANZ said the conflict created significant uncertainty for the economic outlook and was already hitting people in the back pocket.
It said the hit to confidence would likely be negative for growth and it was reasonable to believe that both firms and households would think twice about making making spending decisions, in case things went from bad to worse.
Consumers were caught in a perfect storm in March, hit by higher fuel prices and rising mortgage rates.
Chief economist Sharon Zollner said the data was even worse in real time than the headline suggested.
"It's not the full story because we can actually look at it as the month evolved, and in the last week of sampling it was (consumer confidence) under 80," she said.
Zollner said the same pattern had repeated across the Tasman where Australian consumer confidence had "dropped like a stone".
