Rev Gabriele Amorth passed away at a hospital in the Italian capital, where he had recently been transferred from the Santa Lucia Foundation rehabilitation facility after his condition worsened.
Tributes to the priest posted by users on Twitter included: "Thank you for your service fr Gabriele!" and "It's hard to imagine Rome without him."
Rev Amorth, who claimed he had performed 70,000 exorcisms, has been referred to as the most prominent exorcists in the Roman Catholic Church.
He served in the Rome diocese, and also published a number of books about his work and the theme of good and evil.
The devil's activity in the world was repeatedly spoken of by John Paul II and, during his papacy, the Vatican released guidance for casting out demons.