There’s video online of Katy performing on a televised Christian music special called ”Day 7.” It aired in 2002, when Katy was 17 years old. (This was six years before she broke out with “I Kissed a Girl.”)
Katy is performing a rock version of a Gospel song called ”Search Me.”
She was still going by her real name, “Katy Hudson,” at the time. She ended up changing it to “Perry,” her mother’s maiden name, to differentiate herself from actress Kate Hudson.