And today as she hit the stage at Radio 1's Hackney Weekend, she had us gawping just as much.
The 'Laserlight' singer showed off her amazing figure as she performed in monochrome striped Motel Rocks jeans and a orange and black crop top.
It looked like Jessie had been taking style lessons from Cheryl Cole who went for the Bertie Bassett look last month (via The Sun).
And she completed the fierce look with a pair of black platform studded boots and her signature bob - which she today revealed to Radio 1's Reggie Yates was in fact a wig.
She said: "It's really windy and really cold and so this wig stays in place."
And she revealed that her real hair is an absolute mess from all the travelling she does.
She also told him that she wore heels - so she wouldn't fall over in the wet. Wouldn't she be better off in flats?
"I wore heels so I wouldn't fall. So I'd be aware of it."
And she added that she loves festivals more than anything because of the people who come along that didn't originally arrive to see her. She said: "One of my favourite things about festivals is seeing the crowds get bigger."
Win a pair of Motel Rocks jeans as seen on Jessie J at Radio 1's Hackney Weekend.
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