The Austria international will spend the season with Hannover.
Wimmer signed from Tottenham Hotspur last summer and went on to make 19 appearances in all competitions.
He found regular game time hard to come by during the latter stages of the campaign however, with his last outing for the club coming against Manchester United in January.
Wimmer, who is currently away on international duty with his country, joins a Hannover side that finished 13th in the Bundesliga.
If the loan is a success the deal could be made permanent.