In an interview with this week's TV Buzz magazine, Sir Tom opened up about the pressures of the show.
He confesses: “This is the hardest thing I’ve ever done.”
The Welsh singer, by far the oldest of the show's four coaches, goes on to explain: “You have to critique people, which I’ve never done. I have to make a decision about somebody’s future and it’s really got to me.
"I’d seen people on other talent shows get upset and thought: ‘That’s just TV.’ But here I am, watching our singers and I end up going: ‘Oh s***,’ and trying to keep it together.”
The Voice continues tomorrow night on BBC One with another round of blind auditions, with successful wannabes going through to the tense battle rounds.
Airing in April, the battles will see two artists from each of the coaches' teams compete in a duet, with each coach having to pick only one of the singers to remain in the competition.
Sir Tom reveals: “For me, the toughest part of the show is the battle rounds, because you have to pick one person over the other.
"One of the hardest was when I had to choose between two female singers who were as powerful as each other, but one was a grandmother and had been around a long time. I was thinking: ‘She has never had a break, so should I take that into consideration?’”
He goes on “I just had to hope someone came up a touch and the other girl did, so that’s what made my decision. It’s very emotional, but that’s what I love about this show – you never know what will happen on the night.”
Meanwhile, recalling his decision to sign up for the show, Tom said he wouldn't agree to any contract before knowing who the other coaches were.
"I went into great detail about who else would be involved before I signed up," he tells the magazine. "I thought about the judges on other talent shows and wondered: ‘How can that person judge a singer when he or she has never been in that position?’ I don’t think you can do that.”
The Voice UK continues tomorrow night on BBC One.