The American singer is one of four judges on The Voice 2017 alongside Will, Sir Tom Jones and Gavin Rossdale.
Speaking ahead of the first round of blind auditions, Will admitted he originally thought the plans to to get Jennifer on the show were "impossible".
He explained: "'She's probably doing a movie or working on an album and she's not going to come all the way to London - no, she's not going to come all the way to Manchester'. Once you realise that we're not even filming it in London that's going to be the deal breaker. Nah, she ain't doing it."
Of course as we all know now, producers did convince (or "tricked", as she joked herself) Jennifer into signing up.
But Will is sure she won't be back for another series.
He said at the launch of this year's show: "I know what's going to happen after this season. Okay, so America in 2012 when I did The Voice, the British were like, 'Oh we love will.i.am, we want him on TV' and America was like, 'Yeah, you can keep him!'
"Now the Brits are going to say, 'We love J-Hud', and America's going to be like, 'No, no, no, we taking her back'. And then she's going to be this big superstar - she's big already, but she's going to have her own show. All these folks are going to be trying to get her because she's so good on TV and America's missing that right now - there's no Oprah, there is none of that."
He added: "This whole time I knew Jennifer and I would see her but I didn't really know Jennifer as a person - we all didn't. And we're going to fall in love with her personality all at the same time."
For now, Jennifer isn't going anywhere with The Voice UK airing Saturday nights on ITV.