On Thursday, Hubbard and his bandmate, Brian Kelley, stopped by "The Ellen DeGeneres Show," where the dad-to-be was treated to a surprise baby reveal.
When Hubbard explained that he and his wife would learn Friday whether their daughter Olivia Rose, 13 months, would soon have a little brother or little sister, Ellen decided to speed things up.
"Don't you want to find out today? she asked.
When the country music star said yes, Ellen whipped out an envelope labeled "Hubbard Baby Results" —and then brought out several surprise guests, including Hayley.
"I thought we were just going to cut a cake or something on Friday," Hubbard said as he prepared for the televised reveal.
Before the couple learned the exciting results, they both guessed they'd be welcoming a son.
"Well, let's see what it is," Ellen said as she and Hubbard's bandmate hit a big red button, setting off two cannons filled with colorful confetti.
A huge sign reading "It's a boy" appeared and the couple hugged each other — before reaching out to hug Ellen, too.
"Wow, this is so unexpected," Hubbard said.
The musician and his wife revealed they were expecting again when Hubbard kneeled down to kiss Hayley's baby bump as they walked the red carpet at Clive Davis's annual pre-Grammys gala.
He later shared a photo of the sweet moment on Instagram.
"The Hubbard family is growing. We are excited to share that little nugget #2 is on the way," he wrote. "We are so thankful and can’t wait to see Olivia be a big sister. What do y’all think ... boy or girl?"