In just the second all-qualifier final since the tour was established 28 years ago, Klizan won 6-2 6-2 in the final in Austria and celebrated by removing his shirt.
Klizan, who had beaten No.1 seed and home hope Dominic Thiem earlier in the competition, converted each of his four break points and won 78 per cent of points on his first serve.
The Slovakian has now emerged victorious in every one of his six tour finals, equalling a record for most victories without defeat at that stage set by Ernests Gulbis.
"Sometimes in the finals I was lucky, sometimes it was hard work and sometimes I was better on court," Klizan said.
"You never know what is going to happen.
"I am just happy to have that kind of statistic, winning six titles from six finals. In doubles, I have four titles from four finals. It is very good and I am very proud."