The Rolling Stones frontman and his 29-year-old girlfriend welcomed their first son in New York today.
Michael and his wife Luisana have both cancelled their work schedules to look after their toddler.
Michael Buble's eldest son Noah, aged three, has been diagnosed with cancer.
In a statement released on wife Luisana Lopilato 's Facebook page, Michael said, "We are devastated by the recent cancer diagnosis of our eldest son Noah who is currently in treatment in the United States."
Michael and Luisana have both cancelled all work engagements to be with their toddler.
"We've always talked a lot about the importance of the family and the love we have for our children.
Luisana and I are going to spend all our time and attention to help Noah to get better, by suspending our professional activities for now."
Picture: Michael Buble's Instagram
"During this difficult time, we ask that you pray for him and please respect our privacy. We have a long road ahead of us and we hope that with the support of our family, friends, fans around the world and our faith in God, we can win this battle."
It is thought that an unexpected trip to the doctor took a turn for the worse when it was thought to be a more serious illness.
Our thoughts are with Michael, Lusiana, baby boy Elias and toddler Noah at this time.
Michael Buble speaks to Smooth about how fatherhood has changed him.mov
The Canadian singer told Kate Garraway how music doesn't define him, but being a father does.