The Pope sat in a wheelchair on a balcony and waved to the crowd that had gathered at Gemelli Hospital in Rome, where he has been receiving care since February 14.
During the brief appearance, the Pope beckoned a colleague with a microphone and then spoke a few words to the crowd, thanking them for all the well-wishes he had received.
Thank you, everyone, said the Pope and gave a thumbs up.
He also acknowledged a bouquet of yellow flowers held up by a woman outside the hospital.
The 88-year-old Argentine-born Francis has been treated for double pneumonia and further complications. His condition has been assessed as critical on several occasions.
The Pope's appearance took place in connection with the traditional Angelus prayer on St. Peter's Square in the Vatican. He usually leads the prayer at noon on Sundays, which is also an opportunity for the Pope to comment on current issues.
The doctors have decided that Pope Francis can return to his residence adjacent to St. Peter's Church, as it is deemed the best place for him to recover.
According to Gemelli Hospital's chief physician Sergio Alfieri, the recovery period is expected to last "at least two months", reports AFP.
