The World Cup leader edged to victory after two close heats at the venue in the north of the city, topping the podium for the sixth time this season.
Croatia's experienced slalom specialist Ivica Kostelic confirmed his return to form by taking third place at the expense of Germany's Felix Neureuther, the winner of the previous City Event held in Munich on New Year's Day.
Hirscher, who has been on the podium of every slalom held this season, extended his lead in the overall World Cup standings to 214 points over Norway's Aksel Lund Svindal.
"Right now it is definitely very, very good. It was so close in every heat," said Hirscher, who will be the hot favourite for the slalom crown in Schladming.
"This is totally different from a normal slalom. You don't have the time to think. You can only be 100 percent. It's full gas and attack or nothing."
In the women's race, Germany's Lena Duerr seized her first World Cup victory after replacing compatriot Veronika Rebensburg, who had shunned the event.
The 21-year-old Duerr beat some of the best slalom specialists on the circuit to finally upstage Slovakia's Veronika Velez Zuzulova, the winner in Munich a month ago.
American Mikaela Shiffrin was third to increase her lead in the slalom World Cup ahead of Tina Maze.
Slovenian Maze, the overall World Cup leader, looked weary after winning a slalom at home in Maribor on Sunday and was ousted in the second run.
- Sports & Recreation