Benedict, 86, who resigned a year ago, sat quietly wearing a long white overcoat in the front row along with other cardinals. It was the first time he has attended a papal ceremony since his resignation, although he and Francis have met several times.
When he reached the front of the basilica to start the ceremony, Pope Francis went greet Benedict, who took off his white skull cap in a sign of respect and obedience to Francis.
Even though the crowd inside the basilica had been asked to refrain from applause during the ceremony, they clapped when Benedict walked in and again when his name was mentioned in an opening address by one of the new cardinals.
Benedict became the first pope to resign in 600 years when he stepped down on February 28, 2013. Francis was elected the first non-European pope in 1,300 years two weeks later.