For the first such visit by a Turkish leader for 59 years, Italian authorities have imposed a 24-hour ban on demonstrations which covers Erdogan's arrival late Sunday to his departure on Monday evening.
A total of 3,500 police have been deployed for the visit.
Nevertheless a sit-in protest by 200 people, organized by a Kurdish association in Italy, was scheduled to take place on Monday not far from the Vatican.
Turkey on January 20 launched its "Olive Branch" operation against Syrian Kurdish People's Protection Units (YPG) militia which Ankara sees as a terror group and a threat to Turkish territory.
The Turkish army and allied Ankara-backed Syrian rebel forces are seeking to oust the YPG from its western border stronghold of Afrin but the operation has faced fierce resistance. "In Afrin, a new crime against humanity is underway," the Kurdish association said.
The pope, who has railed against the horrors of war and weapons of mass destruction, was likely to raise the Afrin issue during his meeting with Erdogan.
Ahead of the meeting, Erdogan's convoy arrived at a deserted Saint Peter's Square, which was under heavy police protection.
The YPG, while considered a terrorist group by Ankara, is allied to the United States in its battle against Islamic State group jihadists.