"It's a girl. I'm very, very excited about becoming a daddy. I can't wait," The Mirror quotes Williams as saying. "The missus is like, 'Don't go telling', and I said 'I won't'."
Williams also joked that he intends to teach his daughter "football, karate and boxing", adding: "That's the first thing she's going to learn to keep people like me and Johnny (best friend Jonathan Wilkes) away."
The Take That star's bandmates Mark Owen and Gary Barlow are also expecting additions to their families this year.