The girl group premiered Shout Out To My Ex on the Radio 1 Breakfast Show after performing it on The X Factor.
Perrie told host Nick Grimshaw: "I mean, we did expect it, didn't we? The song speaks for itself.
"Who doesn't relate to this song? It relates to everyone. Jes always says it's like a happy, heartbreak song."
Perrie and Zayn got together in 2012 shortly after Little Mix won The X Factor and announced their engagement in August 2013.
They split up last year after Zayn left One Direction.
It followed allegations that he'd cheated on Perrie.