The unemployed 39-year-old from top-flight Rapid Vienna's "ultra" wing was spotted performing the banned gesture during a match in August 2016 and sentenced in Vienna on Monday.
"I didn't really give it much thought. But it clearly wasn't a good idea," the skinhead told the court, saying he had had "a few beers and spritzers" before the game.
Similar convictions are relatively common but usually the sentences are suspended. In this case, however, than man had a previous conviction for wishing Hitler happy birthday on Facebook in 2013.
Rapid Vienna is Austria's most successful club with 32 league titles but its hardcore "ultra" supporters have a bad reputation.