The last three were released hours after the militants released a group of four Koreans. On Wednesday 12 were set free, out of 23 originally held. In late July, two of the male hostages were killed by the Taliban.
None of the Koreans released Wednesday and Thursday, who were handed over to the International Committee of the Red Cross in Afghanistan's Ghazni province, spoke to reporters.
An agreement was reached to release the remaining captives at face-to face talks between South Korean and Taliban negotiators two days ago. Indonesian diplomat Heru Wicaksono mediated in the talks. It remains unclear whether South Korea paid a ransom for the hostages.
The Taliban hi-jacked the volunteers' bus en route from Kabul to Kandahar on a humanitarian mission. Militants earlier demanded that South Korea pull its military contingent out of Afghanistan, and that the Afghan government release imprisoned Taliban fighters in exchange for Korean hostages.
However, at Tuesday's talks the Islamist group dropped their demand for the release of its members. South Korean Presidential spokesman Cheon Ho-seon announced after the direct negotiations that an agreement had been reached to release the remaining volunteers "on the conditions that South Korea withdraw its troops stationed in Afghanistan by the end of the year, and impose a ban on its Christian missionary activities in the Southwest Asian country."
The Taliban had released two female hostages after a round of negotiations on August 12.
The latest talks were held in local offices of the International Committee of the Red Cross (ICRC). The ICRC participated in the three previous rounds of negotiations.