Gebre Selassie, 25, has signed a four-year deal.
"We are happy that Theodor decided on Werder Bremen despite a number of other offers. He is a very talented right back who confirmed our good impressions with some good performances at the European Championship," Bremen's director of sport Klaus Allofs told the club's website.
Gebre Selassie, born to an Ethiopian father and a Czech mother, started all four of the Czech Republic's games at Euro 2012, including the 1-0 quarter-final defeat by Portugal on Thursday when the right back was marking Cristiano Ronaldo.
"The decision for Werder Bremen is exactly the right one. Werder is a club with a lot of consistency and tradition which always had high goals. I would like to continue my successful season in Liberec in Bremen," said Gebre Selassie.
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