According to the Vatican Insider, Polish archbishop Konrad Krajewski, who is in charge of giving alms, approached the men while they were sleeping rough outside the Vatican to invite them to the morning mass on Tuesday.
Pope Francis also invited his household staff to the mass, which was held in the Domus Santa Marta, in order to give it a “family atmosphere”, the report said. Following the service, all those present went to breakfast in the church's dining hall, and Krajewski introduced the homeless men to Pope Francis.
The Pope is known for his commitment to helping the poor, and has spoken out against greed in the Church.
Other celebrations included a birthday cake presented at the Vatican by children on Saturday, and a visit from the Pope's favourite football team, San Lorenzo, who flew in from Argentina for the occasion and are expected to meet with him after his public mass on Wednesday.
The Pope also received posts on Twitter with the hashtag '#AuguriFrancesco' in many languages, and a video from the Vatican's television channel, showing some of the most significant images from the first nine months of his papacy, was aired.
See the Pope's birthday messages in the gallery below: