"The traditional Olympic truce acquires special importance this year," he told pilgrims and tourists at his weekly general audience.
Delegations from the two Koreas will march together under a single flag and athletes will compete as a single team in some sports at the Winter Games starting on Friday in Pyeongchang, South Korea.
"This allows for hope for a world where conflicts can be resolved peacefully through dialogue and reciprocal respect, as sport teaches us to do," he said.
"May these Olympics be a great feast of friendship and sport," he said, adding that the Vatican was ready to back any "useful peace initiative that favours peace and encounter among peoples".
Francis has in the past called on all nations to support dialogue to ease tensions on the Korean peninsula and to work for a legally binding ban on nuclear weapons..
Last year he said a third country, such as Norway, should try to mediate the dispute between North Korea and Washington, to cool a situation that had become "too hot" and posed the risk of nuclear devastation.
The pope, who is a soccer fan, said he would be accompanying the Games with his prayers.
(Reporting by Philip Pullella; Editing by Alison Williams)
