The singer looked like she was having a Ball as she took to the stage in a see-through outfit, which showed off her incredible figure.
However, before the show she revealed on Twitter that she wasn't feeling quite as great as she was looking.
"Time to rest before glam time! I refuse to be sick! No no no sickness! You ain't gonna win! Muhahahaha!" she said.
On stage, wearing a dress made of black mesh, Jessie belted out a string of her hits, and also treated fans to the first live performance of her new single 'Wild'.
Jessie was also rocking her new shorn blonde 'do after shaving her head for Comic Relief in March, something which she recently hailed as one of the highlights of her career so far.
She told Glamour magazine: "Obviously, shaving my head was a massive highlight. I've been wanting to do it for a long time but I wanted to be famous enough that it would raise a lot of money."