"Clemens has been playing to a very high level for years," coach Thomas Schaaf said.
"If his consistency can rub off on the rest of the team it'll be fantastic. His experience and personality make him a very important player for us."
Fritz, 31, is a versatile defender who mostly plays at right-back.
He joined Bremen from Bayer Leverkusen in 2006 and has made over 160 Bundesliga appearances.
The former Karlsruhe defender has also played 22 times for Germany, scoring twice.