The 'Haven't Met You Yet' hitmaker took to social media to confirm the devastating news that his son Noah, three, - who he has with his wife Luisana Lopilato - has been diagnosed with the illness and is currently undergoing treatment in the United States.
In a statement released on Michael's Facebook page, they said: “We are devastated about the recent cancer diagnosis of our oldest son Noah who is currently undergoing treatment in the US. We have always been very vocal about the importance of family and the love we have for our children.
“Luisana and I have put our careers on hold in order to devote all our time and attention to helping Noah get well. At this difficult time, we ask only for your prayers and respect for our privacy. We have a long journey in front of us and hope that with the support of family, friends and fans around the world, we will win this battle, God willing.”
The tragic news comes not long after the 41-year-old singer - who also has eight-month-old Elias - admitted he didn't realise the “perspective” having a child would give him.
He shared: “The only regret that I have in my life is that I took this long to have kids, because I had no idea the perspective it would give me. I had no idea how much I would love being a dad.
“That's it, that's all I care about ... I love them too much probably, if there was such a thing. It's made everything else so insignificant, moments that I was afraid of and moments that would overwhelm me have now become a joy because I've realised how not serious they are compared to what is really important, which is Noah and Eli and that's it.”