The Bavarian club confirmed the deal on Thursday as the United States international's 10-day trial at the club came to an end.

Bayern coach Jurgen Klinsmann has also left the door open to the former Bayer Leverkusen player earning a longer stay in the Bundesliga.

"It is up to him," he said.

"He can recommend himself for a longer relationship."

Donovan will be available to play in the Bundesliga from January, when the transfer window reopens.

However, Klinsmann rejected suggestions that the arrival of another striker spelled the end of Lukas Podolski's time in Munich.

"I want to start the second half of the season with four strikers to have more alternatives if one of them should pick up an injury," Klinsmann said.