Under the terms of the deal, South Korea agreed to end missionary activities by Christian groups in Afghanistan.
Relatives of the hostages who erupted in cheers on hearing news of the agreement are now anxiously awaiting the hostages' return.
"It is like a dead child is coming back to life," Lee Hyoen-Ja, a relative of one of the kidnapped Christian aid workers, told South Korea's JoongAng Daily on Wedneday.
Seo Jeung-Bae, whose son and daughter were among the hostages, told AFP: "I want to see them and hug them hard now.
"I had not doubted for one moment that the Taliban would return my children some day, as the Taliban are also human beings and have their own families."
At Seoul's Saemmul Church, which sent the volunteers to Afghanistan, officials said the focus now would be on looking after the released hostages and their families.
"Our work for now will be to make sure the freed hostages return safely and have the time to recover, and to make sure the family members of the two who were sacrificed are comforted," Bang Yong-kyun, pastor, told Reuters.
The group of 23 volunteers from the church were seized on July 19 from a bus as they travelled through Afghanistan's Ghazni province.
The kidnappers killed two male hostages early on in the crisis, but released two women as a gesture of goodwill during a first round of negotiations.
As news of the release spread, other South Korean churches said the kidnapping crisis had led them to rethink their evangelical activities.
The National Council of Churches in Korea, one of the largest groups representing the country's Protestants, said in a statement it would abide by the government's pledge to end missionary work in Afghanistan.
|Relatives have reacted with joy following news|
an agreement had been reached [AFP]