He will join fellow new arrival Mike Hanke in leading the line for Christian Streich's side at home and in Europe next season, and should he impress, the Black Forest club have secured an option to make the deal permanent.
The 24-year-old did not feature for the Wolves last season due to a serious knee injury.
However, he is now on the road to recovery and should be fit to help Freiburg next season.
"We are delighted to have signed a highly-interesting player who, despite being only 24, has already gained lots of experience," said Freiburg's interim director of sport Klemens Hartenbach.
"We are aware that Vaclav needs to follow a personal training regime to start with and there is no set date for him to start training with the team."
The former Viktoria Plzen forward impressed as part of the Czech Republic team at Euro 2012 and he will be looking to make his long-awaited Bundesliga debut next season.