The encounter will be particularly poignant coming after several days of deadly violence as Muslims have protested against a US-made film that mocks Islam.
Before his talks with the Muslim leadership, he will also meet Prime Minister Nagib Mikati, a Sunni, and parliament speaker Nabih Berri, a Shiite.
Lebanon has an unwritten but rigorously followed tradition that the three top jobs are always reserved for members of those respective faith communities.
He will also deliver a speech to the assembled dignitaries on the common vocation of Christians and Muslims to be religions of peace.
Thousands of people, mostly Christians and including many children, lined the road leading to the palace in bright but pleasant sunshine, hoping to catch a glimpse of the pope.
Lebanese and Vatican flags fluttered, and there was a festive atmosphere on the streets.
Zeina Khoury, a Maronite who lives nearby, said she, her husband and two children got up at 6:00 am to make sure they could find a place along the route.
“This is a blessing for Lebanon,” she said. The pope’s visit is “important because it can bring us peace and because it reminds us of the importance of living together.”
“I brought my children to see the pope … because it could be the only chance they will ever have in their life.”