In an interview for Friday Night With Jonathan Ross to be screened this week, the former Take That singer said he thought he was destined to stay single until he met American actress Ayda Field.
He said: “I thought I was going to be a bachelor ... I was introduced to Ayda and things just changed. She's a wonderful person and I'm in love.”
Ross probed whether the pair were ready for children and the singer said it could be in the next couple of years.
He added: “She's really broody and I'm getting there.”
The 35-year-old also restated his desire to perform again with his old group Take That.
He said: “We've got together, done bits and bobs. I can't say much, but yes, I hope so.”
Williams performs his new single You Know Me on Ross’s chat show.