Hanson, 35, first shared a photo of their new bundle of joy, Claude Indiana Emmanuel Hanson, on his Instagram Story Friday, along with photos of their baby boy on their Instagram pages.
"Happy Birthday to my best friend and beautiful wife Natalie. Overjoyed to share the gift of a lifetime, little Indiana Hanson, born 12.26.2018," Hanson wrote on his Instagram page, alongside a photo of Natalie with Indiana in the hospital.
Natalie also shared a photo of Indiana in an adorable onesie, adding, "Claude Indiana Emmanuel Hanson welcomed with love 12.26.18."
Hanson's representative told Entertainment Tonight that Indiana was born at a hospital in Tulsa, Oklahoma.
"Our new little man, Indy, is the best gift our family could imagine. His arrival brings with it a new sense of adventure and excitement for the future," the couple said in a statement to the outlet.
Hanson and Natalie are also parents to daughters Penelope "Penny" Anne, 13, and Wihelminia "Willa" Jane, 6; and sons Jordan Ezra, 16, River Samuel, 12, and Viggo Moriah, 10.
Hanson and his brothers Isaac and Zac make up the band Hanson. The group shot to fame with their 1997 hit "MMMBop" and continue to record, releasing their latest album String Theory in November. They also have a fourth brother, Mac Hanson, who recently began his own music career as the frontman for Joshua and the Holy Rollers.
In an interview with Entertainment Tonight last year, Zac, Isaac and Hanson suggested their children could follow their fathers into the music business.
"It's funny, though, Isaac's oldest son is playing guitar, Taylor's oldest son is playing keyboard and my oldest son just started playing drums," Zac said.
"I mean, they're around music all the time," Hanson chimed in. "If somebody didn't pursue music, in between our kids, I'd be surprised. .. Performing is a great, amazing gift, and if you have it, you kinda have to do it. If you don't have it, you can't fabricate it. So, the question is really whether or not they have that need. We joke it's kinda like having an addiction that you turn into a job.
However, Hanson said it was important for his children to do what they love, and not to force them into the business.
"Making music, whether it's in the studio or onstage, if it's there, then of course you want them to do whatever makes them happy," the singer said. "That's really all you can hope for."
Photo credit: Instagram/Natalie Hanson