Pacemen Glenn McGrath (3-17) and Shaun Tait (3-39) reduced the match between the defending champions and the Cup debutants to a no-contest when they wrecked Ireland's top order with their opening spells.
Ireland could never recover after being reduced to 12-4 in the fifth over on a pitch having pace, bounce and movement.
They were eventually dismissed for 91, a total which was too small to put pressure on in-form Australia.
The match was completed before the lunch-break as Australia raced to the target off just 12.2 overs despite changing their batting order.
Hard-hitting Adam Gilchrist (34) and Michael Hussey (30 not out) ensured an easy victory with a brisk 62-run stand for the opening wicket.
Hussey, a middle-order batsman opening the innings for the first time, got valuable batting practice ahead of his team's last two matches against New Zealand and Sri Lanka.
Both wicketkeeper-batsman Gilchrist and Hussey toyed with the Irish bowling, gathering runs with consummate eas