His visit, the first by a Pope since 1985, aims to highlight the human cost of decades of conflict in the vast central African country.
Despite being rich in minerals, millions of Congo's people have been forced from their homes and live in poverty.
Francis, who struggles to walk because of a knee ailment, was wheeled along the red carpet at an airport on the outskirts of the capital Kinshasa.
Along Boulevard Lumumba, the arterial road connecting the airport to the city, cheering crowds gathered for a glimpse of the pontiff.
Speaking before the Pope's arrival, Father Edward Isonge of the Archdiocese of Kinshasa, said he hopes the Pope's visit will unite the people.
"...all the world is watching what is happening here in Congo. They are already talking about what is happening in the east. With the Pope's arrival the hope is that his presence here will contribute to making people understand what is going on in the east part of the country and this may be a trigger for peace."
Congo has some of the world's richest deposits of minerals including gold, cobalt, lithium and diamonds.
But the abundant resources have stoked conflicts between militias, government troops, and foreign invaders.
Eastern Congo has also been plagued by violence connected to the long and complicated fallout from the 1994 genocide in neighboring Rwanda.
Francis, whose trip was originally planned for last July, had been scheduled to visit the eastern city Goma.
That part of the visit has been scrapped because of renewed fighting between government forces and rebels from the M23 group.
Instead on Wednesday (February 1) the Pope will meet victims of violence from Congo's east in Kinshasa.
An estimated 5.7 million people are internally displaced in Congo and 26 million face severe hunger, according to the United Nations.
About half of Congo's 90 million population are Roman Catholics.
The Catholic Church plays a crucial role in the country running schools and health facilities, as well as promoting democracy.
Francis will stay in Kinshasa until Friday (February 3) morning, when he will fly to South Sudan, another country grappling with conflict and poverty.
