The 37-year-old singer wasted no time in sharing the happy news with his fans, posting a picture on Instagram taken in the hospital.
"Overjoyed and filled with gratitude at the arrival of our son Noah Buble. Born this morning, August 27th at 2.26 am," he wrote next to the adorable photograph, which shows his smiling wife cradling their tiny newborn as he proudly looks on.
Luisana, an Argentine lingerie model and actress, gave birth in Vancouver, Canada.
Messages of congratulations are already pouring in for the couple, who married in several emotional ceremonies in their two countries.
Among the first was One Direction star Niall Horan, who was quick to join well wishers around the world, tweeting, "Congrats to my good friends @michaelbuble @lulopilato on the birth of little baby Buble! Soo exciting! Can't wait to meet the little one."
New mum Luisana, 26, first revealed that she was expecting back in January via her website, telling fans: "Mike and I have some big news for you." Her message was linked to the first scan of the baby.
His plan for fatherhood, Michael says, is "to try to be a good dad like my dad was and like his dad was. If he turns out to be a great, macho hockey player or a gay ballet dancer, I'll be just as happy as long as my kid is happy."
The couple spent the pregnancy arguing about what the baby would be called, with Luisana putting forward Spanish names and her husband "messing with her" by suggesting "Thor".
Michael wears his heart on his sleeve when it comes to his lady. Earlier this summer he paid tribute to Luisana, 26, in a song called Close Your Eyes.
The chart-topper described the song as a testament to how much "she helps carry me...how she shares the load with me. I was just thinking, “You’re always the one that pulls us through.’
"It’s an unashamedly heartfelt tribute to the strength of women, and how much men depend on them. And people call women the weaker sex," he added. "How foolish is that?"
The song includes the lyrics: "You're one of a kind/Thank god you are mine."
Love blossomed for the couple in 2008 when his record company threw a party after one of his concerts in Buenos Aires. The head of the label introduced him to Luisana, the star of a hit soap in her native country.
A year later the singer presented her with a diamond engagement ring he'd helped design.
His spokeswoman said of the romantic proposal: "Michael proposed to his girlfriend, Luisana, in November, in front of her family in Argentina. They're ecstatic. They're adorable, in love and laugh all day long."