Buble told the Daily Star that he had worked on a track for the follow-up to 2001's Swing When You're Winning, and said that he and Robbie had become good friends.
"I got to know Robbie through The X Factor and I love him," Buble explained. "The song is for his new swing album and it's so good. We had too much fun making it."
He also told of how the 'Candy' singer had been a sympathetic ear for him, and that the two talked about their troubles.
"Robbie has probably been more open than I have with certain things," he admitted.
"I'm pretty open but he's bared his demons.
"I have the same demons, so we talk about all the things I think about as I don't have other people to talk to them about. It's pretty awesome."
Robbie Williams performed at this year's BRIT Awards
"I have truly enjoyed my conversations with Robbie. Both of us were dealing the insecurity, bith of us were dealing with everything about the way we could live, both of us probably do what we do too much."
It has also recently been rumoured that Adele might appear on the record, with sources telling The Sun the two got on famously when she was in LA ahead of the Oscars, but that any plans to work together were still in the early stages.
Below: Mrs Michael Buble and more: the hottest wives and girlfriends in music