The man has been in custody since August 2024, when he and two others were arrested for planning an Islamist terrorist attack.
Police searched his home and found chemical substances and technical equipment. The 21-year-old admitted that he planned to make a bomb and said he would "try to kill as many people as possible."
The terrorist threat led to the cancellation of all three of Taylor Swift's scheduled concerts in Austria.
The man is an Austrian citizen, but is said to have sworn allegiance to IS and could now face up to 20 years in prison. The CIA tipped off the Austrian police about the terrorist plans.
The prosecution has not announced whether it plans to prosecute the two other arrestees.
