《On Fire》是一首由Katy Perry演唱的英文歌曲，該歌曲是《Witness》專輯的第二主打歌曲。
歌詞如下：
Chorus:
On fire, on fire, let it burn
On fire, on fire, let it burn
Just like the sun comes up
We'll go down in flames
But I'm with you now
Verse 1:
This is not the end
But a new beginning
And I'm here with you
Through the highs and lows
We'll be alright
Chorus:
On fire, on fire, let it burn
On fire, on fire, let it burn
Just like the sun comes up
We'll go down in flames
But I'm with you now
Bridge:
This is our time
To rise up and shine
We're on fire, we're running wild
With all the souls in the world
This is our song
Our fight, our song
We're on fire, we're one
Chorus:
On fire, on fire, let it burn
On fire, on fire, let it burn
Just like the sun comes up
We'll go down in flames
But I'm with you now
Outro:
We're on fire, we're on fire, we're on fire.