World Day of Peace is a holiday of the Roman Catholic Church, celebrated annually on January 1 on the Day of the Celebration of Our Lady of Mary. On December 8, 1967, Pope Paul VI proclaimed World Day of Peace.

For several years, it was celebrated on the first day of each new year. On December 17, 1969, the UN General Assembly proclaimed World Peace Day as an official holiday.

World Peace Day is a day off at the Vatican, while in Brazil it is celebrated as World Fraternity Day.