Maierhofer has not featured for Wanderers since December, and he told the club's official website: "I'm 27 years old and I want to be playing games. I'm happy to be here. I'm here for 28 days and hopefully I can help move the team up the league.
"I have no problem dropping down to the Championship to get games. This is still a very tough division. When I arrived here and saw the stadium, the superb pitch, it makes me hungry to play."
Maierhofer, whose ability is not only limited to his obvious aerial threat, is available to make his debut in Tuesday night's Championship clash at Plymouth.
And Robins boss Gary Johnson added: "We knew signing Stefan was an option available to us if Chris Iwelumo decided to return to Wolves. He comes highly recommended from Mick (McCarthy) and is a different type of player to what we already have in the squad."