Juergen Chrobog and his wife and three children were taken hostage while travelling by car from the port city of Aden to Shabwa, 480 kilometres east of the capital, Sanaa.
Germany's Foreign Minister Frank Walter Steinmeier confirmed that the family had been released.
The kidnappers had demanded that the Yemeni government free five tribesmen jailed on charges that included murder.
It is not clear if their demands were met.