"To all the amazing daddies out there that love their kids unconditionally like my mommy's daddy and my daddy, too… HAPPY FATHER'S DAY! -York?," the snapshot was captioned.
"The best present we worked and prayed so hard for is finally here. He's got my fingers and big eyes and his daddy Erik's mouth and chin," Tyra captioned an Instagram photo of a baby hat to announce York's surprise birth to the world.
"As we thank the angel of a woman that carried our miracle baby boy for us, we pray for everyone who struggles to reach this joyous milestone. York Banks Asla, welcome to the world," she wrote.
Tyra and Erik — a 52-year-old Norwegian photographer — began dating in 2013.
"Some mornings you wake up, and you're like, 'Where am I? I don't know what's going on. And I know it's not a good idea for me to drive right now because I did not sleep,'" she said in March 2016.
"So I balance that and his dad helps, and we go back and forth so that's good," she added.
In another previous interview, Tyra candidly opened up about finding a work-life balance while raising her now one-year-old son.
"My secret to balance is to focus on one thing at a time. I used to be the most amazing multitasker, doing three things at once," Tyra said in November 2016. "Not anymore, now that I have my son. I think that’s Mother Nature’s way of saying this life you created takes all of your brain power."
"Now I’m like, 'Mommy’s going on a conference call,' and I give him to his dad," she continued. "My son, as he gets older, he’s getting a lot more clingy so he wants to be held a lot more and be close to Mommy a lot more, so I have to do things fast."
Check out the gallery to see more cute photos of baby York!