A day before the event, Erik posted a photo of the rehearsal with the orchestra.
Accompanied by a 200-member orchestra, Santos, 31, sang Ps. 97 with 1,000 choir members from various dioceses at the Quirino Grandstand in Manila.
The highly anticipated event, which was concelebrated by 2,5000 priests and attended by 200 bishops, was estimated to have had some 6 million people in attendance with millions more watching on television.
Santos, who rose to fame after winning an ABS-CBN singing competition in 2003, had referred to his part in the papal mass as the most important performance of his decade-long career.