The pontiff on Wednesday asked for prayers for "both those of the South and of the North" of Korea.
He said the meeting this week on the Korean Peninsula was an opportunity to start dialogue.
US-allied South Korean President Moon Jae-in and North Korean leader Kim Jong Un will meet on Friday in the Demilitarised Zone between the Koreas.
The summit that could pave the way for US President Donald Trump's planned meeting with the North Korean dictator.
Francis, speaking at the Vatican, called the summit "a favourable occasion to start a transparent dialogue and a concrete route toward reconciliation and regained brotherhood with the aim of guaranteeing peace on the Korean Peninsula and in the entire world".
Reporting by Associated Press.
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