The 86-year-old Pope arrived at Kinshasa's international airport at 14:33 local time and was greeted with a welcoming ceremony.
As part of his visit to the African nation, the Pope called Congolese President Felix Tshisekedi and addressed the country's authorities, civil society and diplomatic corps.
The Pope addressed Congolese government authorities and the diplomatic corps from the presidential palace. "Hands off the Democratic Republic of Congo. Hands off Africa. Stop suffocating Africa: it is not a mine to be exploited or a land to be plundered," Francis said in his address.
In the Congo there are conflicts between militias, government troops and foreign invaders that cause wars, displacement and famine. This is related to the region's vast mineral wealth.
"It is a tragedy that these lands, and in general the entire African continent, continue to endure various forms of exploitation," said the Pope, who added that in Congo, "the poison of greed has stained its diamonds with blood."
The Pope also referred to the violence plaguing eastern Congo. The Congolese people are struggling to preserve their territorial integrity "in the face of deplorable attempts to fragment the country," Francis said. According to the country's government, the Rwandan-backed M23 rebel group is fighting government troops in the east.
Pope Francis' six-day trip also includes a stop in South Sudan. His 40th apostolic trip abroad and his fifth to Africa since assuming the Vatican headship in 2013.