"The remaining four Turkish nationals were released today as a sign of goodwill and as an Islamic and humanitarian gesture of respect to the Muslim Turkish nation," the insurgents said in an emailed statement.
"They were delivered to relevant Turkish authorities."
Four other Turkish engineers on board the helicopter were freed on Sunday.
The Islamist militants made no reference to a Russian, a Kyrgyz national and an Afghan also taken hostage after the crash-landing on April 21 in Logar province, a Taliban stronghold south of the capital Kabul.
Turkey, one of only two Muslim-majority members of NATO, has around 1,800 soldiers serving with the US-led military coalition, but they do not take part in combat operations.