The Argentinian Pope inherited the @pontifex account when he was chosen by his brother cardinals to succeed Benedict XVI in March.
Benedict had attracted 2.5 million followers since the papal Twitter account was launched in December last year. But the subsequent growth in numbers under Francis, from 2.5 million to seven million, has been dramatic. He has tweeted on just 76 occasions - meaning that each tweet has, on average, earned him an extra 59,000 new followers.
He still lags behind stars like Lady Gaga, who has nearly 39 million Twitter followers, and Beyonce, who has 9.5 million and remains a long way behind Barack Obama – the US President has 33 million followers.
But he is comfortably ahead of Stephen Fry, on 5.9 million, and Jeremy Clarkson, with two million. David Cameron is followed by just 352,000.
"With his presence on the social network, Pope Francis is attracting an increasing number of people, especially the young, who are the internet's biggest users," L'Osservatore Romano, the Vatican's newspaper, wrote this week.
Francis, like his predecessor, tweets in nine languages, including English, Italian, Latin, Arabic and French. Reflecting the Pope's South American heritage, Spanish is the most popular of the feeds, with more than 2.7 million followers.
The second largest group of followers, at 2.6 million, are English speakers. The third most popular language is Italian, followed by Portuguese, French, Latin, German, Polish and Arabic, the last with 68,000 followers.
Unlike celebrities or many ordinary people on Twitter, the Pope does not give insights into his daily routine, but instead sends out snippets of religious instruction.
"Consumerism has accustomed us to waste. But throwing food away is like stealing it from the poor and hungry," was one recent tweet, reflecting his concern for the poor and the plain-speaking style he has introduced since being elected pontiff.
The @pontifex handle was launched on Dec 12 by Benedict...