The Voice, which continues tonight on BBC, will see Jessie coach a team of 10 artists, one of which will hopefully land themselves a record deal in the final in June.
But she warned the singers in her group today: “The contestants have to realise they need to raise their game.
“I’m not saying it’s easy – I know how it feels to step out on a stage in front of millions of people I don’t know.
“When I performed on the X Factor last year, I was shaking like a leaf. But it’s got to be done and they need to embrace it."
The 23-year-old singer has been dubbed "the evil one" by her fellow panelists - Sir Tom Jones, Will.i.am and Danny O'Donoghue - but it's a title she loves.
"I may make them cry but they always come back the next day and say, ‘Thank you for the tough love – it’s what I needed’," Jessie tells the Daily Mirror today.
“You’ve got to say to yourself, ‘Look at me. I’m living my dream. I wake up every day and do what I love’.
"You’ll never hear me complaining and I never expect to hear my acts complaining either.”
The Voice UK airs tonight at 7PM on BBC One.