Germany's foreign ministry did not identify the freed detainee, saying only that the person was still prohibited from leaving Turkey.
German-Turkish relations have sharply deteriorated, especially since a failed coup in July 2016 against President Recep Tayyip Erdogan and a subsequent wave of arrests.
Germany charges that several German or dual-nationality citizens imprisoned in Turkey, most prominently Die Welt daily correspondent Deniz Yucel, are being held for political reasons.
Turkey last week released human rights activist Peter Steudtner, who has since returned to Germany.
The German foreign ministry spokesman said the latest detainee freed had been released on October 22, but refrained from revealing the identity at the family's request.