On the first leg of the trip, Moon will meet with Pope Francis at the Vatican on October 29 to discuss peace on the Korean Peninsula and efforts to end the pandemic, presidential spokesperson Park Kyung-mee said.
Moon and Pope Francis are expected to exchange their wisdom to promote peace on the Korean Peninsula and resolve pending global issues, such as pandemic, poverty and climate change, Yonhap News Agency quoted Park as saying.
Moon plans to discuss with other world leaders tackling the climate crisis, the Covid-19 pandemic and how to foster global economic recovery during the G20 summit set for October 30 and 31.
After Italy, Moon will visit Glasgow, Scotland to attend the COP26 on November 1 and 2.
Reducing greenhouse gas emissions will be high on the agenda at the UN climate talks, where Moon will deliver a keynote speech.
South Korea's decision to reduce emissions will be reported to the COP26 talks, officials said.
On the last leg of the trip, Moon will make a state visit to Hungary on November 2.
Hungary erected a monument in memory of the 25 South Koreans killed in the 2019 deadly boat sinking in Budapest.
The memorial stone was set up near the accident site in the Danube River, where the Korean tourists aboard a sightseeing boat went missing after the vessel collided with a bigger cruise line.
On November 2, Moon will visit the site and pay tribute to the victims, the presidential office said.
Moon will hold bilateral meetings with Hungarian President Janos Ader and Prime Minister Viktor Orban on November 3.
In Budapest on November 4, Moon will hold a summit with the prime ministers of the Czech Republic, Hungary, Poland and Slovakia in the second summit between South Korea and the so-called Visegrad Group.