The score was locked at 3-3 before Australia progressed after winning the shootout 5-3.
Louis D'Arrigo opened the scoring in the first half before the Thais equalised on the stroke of half time then took the lead 2-1 early in the second half.
Prolific John Roberts equalised before the Thais took the lead again to make it 3-2.
With Thailand defending deep, they looked to have held on till Roberts netted an equaliser in time added on in a thrilling finish to a fabulous game.
Australia then held their nerve to score all their penalties in the shootout with Bryce Bafford confirming the decisive goal to send the Joeys into the final.
Australia will now face Vietnam in the final. The Vietnamese defeated Cambodia in the other semi final.
This article was originally published at: http://www.footballaustralia.com.au/article/joeys-stunning-win-puts-them-into-aff-final/g2zhxgvcvswr1tzxde4f4wftl.