The singer revealed on The Graham Norton Show on Friday night (November 2) that he feels everything has changed since the birth of his daughter Theodora.
Williams said of fatherhood: "I really do love it. I was worried before she came - I'd been a popstar since the age of 16 and I'd never done anything for myself and then all of a sudden I was being asked to take care of this life.
"I thought I might be this selfish person but you just melt. The baby came out and everything changed, cosmically, spiritually, life, everything."
He added: "I'm a new parent and I've still got that euphoria and she hasn't p*ssed me off yet."
The 38-year-old's wife Ayda Field gave birth to Theodora Rose Williams on September 18.
Williams also discussed the thought process behind the name Theodora, saying that he wanted to avoid ridiculous names associated with celebrity babies.
"We wanted to call her Teddy but that's bordering on celebrity nonsense and we thought what if she doesn't go into showbiz and needs a professional name, so Theodora is her professional name and Teddy is the name she goes by at home."
He also admitted to Norton that he once called Gwyneth Paltrow and Chris Martin's daughter Melon rather than Apple.
"We were at my house in Los Angeles and the Coldplay boys had been over for a game of football and Gwyneth turned up," he said.
"I was like, 'Gwyneth Paltrow is in my house', and as she walked towards me I kept saying in my head, 'Say something to Gwyneth Paltrow, say something to Gwyneth Paltrow' and I said, 'Does Melon want some Apple?'"
Williams is on course to achieve his first number one single in eight years with 'Candy' this weekend. The single sold over 73,000 copies on its first day of release.
Watch Williams perform 'Candy' on last week's X Factor below: