Speaking on the Jonathan Ross show, Jessie J revealed she got the call last autumn about the new BBC One talent series.
"It was a bit scary, I was only 12 months into my career," Jessie admitted.
But she added: "Being on the show is amazing. Sitting next to the likes of Tom Jones and will.i.am has been brilliant."
And the 'Domino' hitmaker revealed she's struck up a surprise friendship with Welsh singer Tom.
She said: "I call him Tommy-o, he’s so sweet."
The Voice UK will start on BBC One this March.