In a statement, the group's bassist, Flea, said it was the NFL's rule that they sing live, but the music be pre-recorded. This is because there are only a few minutes to set up the stage.
The admission came after observers noted Flea and his bandmates weren't plugged in while performing Sunday at MetLife Stadium in East Rutherford, N.J.
According to Flea, the Chili Peppers haven't done any sort of miming since the 1980s. The band checked with fellow musicians and consulted with headliner Bruno Mars, and then decided to the Super Bowl Halftime show anyway, calling it "a surreal-like, once in a life time crazy thing to do and we would just have fun and do it."
Flea said the group pre-recorded a unique instrumental track for the show. He didn't directly address whether Mars also recorded instrumental tracks for his appearance, though he said Mars was aware they did.
A record 115 million people tuned into watch Mars and the Peppers, besting audiences of 114 million for Madonna and 110 million for Beyonce.
The Associated Press contributed to this report.