The Kaiser Chiefs frontman, 36, looked slimmer and appeared to be sporting straighter teeth on his debut on the BBC1 singing contest.
But the singer dismissed reports that he changed his looks for his new TV job.
He told Radio Times : "Everyone's saying 'You lost all that weight and had your teeth done for TV' but I only got the job on The Voice two weeks before we started filming.
"If I'd done all that in a fortnight, people would want the number of my clinic!"
He also suggested that previous winners were to blame for not making it as stars, once they left the TV show.
"They didn't see it through. That sounds harsh, but it's not like you go straight to number one when you get a record deal," he said. "That's where the hard work starts."
Wilson said he would not sign up for series four unless his fellow coaches - Kylie Minogue, Sir Tom Jones and Will.i.am - do.
"It totally depends on whether the other coaches sign up. I'm happy to wait and see what they decide," he told the magazine.
Asked why he signed up to The Voice in the first place, he said: "I had a (Kaiser Chiefs) record coming out and I wanted people to hear it - it would be disingenuous to say otherwise. But I've ended up really enjoying it."