Pope Francis drew more than 6.6 million people to his audiences, Masses and other events in Vatican City since his election in March.
His predecessor, Pope Benedict XIV, attracted 2.3 million people for the whole of 2012.
The Vatican said the figures were based on the number of tickets issued for papal events, as well as on estimates of crowds attending weekly appearances by Francis at St Peter's Square.
The former Archbishop of Buenos Aires named himself Francis after a 12th Century Italian saint who turned his back on an aristocratic lifestyle to work with the poor.
The BBC reports he has adopted a markedly less formal tone than previous popes, underlining his reputation for simplicity and humility. He has also eschewed some of the more regal trappings of office and called for power to be devolved away from the Vatican.
In December, Pope Francis was named Time magazine's Person of the Year.