Staging a comeback for Pakistan in the low-scoring contest, 15-year-old Ali Raza bowled a double-wicket maiden to turn the tie on its head.
However, Ali Raza's death-over heroics went in vain as Raf MacMilllan hit the winning runs in the 50th over to seal Australia's one-wicket win over Pakistan.
Australia will meet defending champions India in the final on Sunday.
Tom Straker led the Australian bowling charge with a six-wicket haul to bowl Pakistan out for 179 in 48.5 overs.
Azan Awais kept Pakistan breathing with a gritty half-century, but the menacing Straker broke through to really dent the opposition's chances.
At 5 down for 79, Pakistan needed a special partnership, and it came from a fifty-plus stand between Awais and Arafat Minhas.
The Powerplay belonged to Australia as Straker took out Shamyl Hussain for 14 followed by Vidler removing Shahzaib Khan, who really struggled during his 30-ball stay for four runs.
Spin was introduced in the form of Raf MacMillan and the off spinner took just two overs to get himself going. Pakistan lost half their side with Beardman cleaning up Haroon Ahmad.
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