Urging them to stop doing evil, the pontiff emphasised while meeting citizen's group Libera, made up of family members of victims of organised crimes that "Blood-stained money, blood-stained power" can be brought to the next life.
This is not the first time that he spoke against the Mafia. In 2005, while he was still known as Jorge Cardinal Mario Bergoglio, the archbishop of Buenos Aires in Argentina, he spoke often of the evils of corruption and authored a booklet on the issue.
Libera actually holds an annual vigil to remember their kin killed by the Mafia, but this is the first time a pope joined them for the event. Over 1,000 people attended the 19th yearly vigil when names of about 900 victims were read individually.
Among those who attended was Don Luigi Ciotti, a priest in Turin, whose mother Vivian Matrangola was shot by the Mafia in 1984. She was the daughter of Renata Fonte, a member of the city council of Nardo.
Pope Francis rejected the church's historic ties with Mafia bosses who even claim to be good Catholics.
A UN estimate placed the joint yearly turnover if the three main Mafia in Italy - the Cosa Nostra of Italy, 'Ndrangheta in Calabria and the Camorra from Naples - at €116 billion.
The pontiff added, "This life that you live now won't give you pleasure. It won't give you joy or happiness ... There's still time to not end up in hell, which is what awaits you if you continue on this path."
A report released on the same day said that threats against Italian local government officials went up 66 per cent since 2010, indicating the continuous operation of the Mafia in the country. Avviso Publico, an anti-Mafia group, said 41 local administrators have been assassinated by the Mafia in the past 100 years, while 243 city governments were dissolved since 1991 because of being infiltrated by organised crime.
The Mafia method to intimidate includes burning public officials' vehicles. They have also gone high-tech by sending threats through email or Facebook