But don't worry — they're happy tears.
The kids are now officially part of the polygamist family, which includes Brown's four wives and their now 17 children.
Interviewer Tamron Hall was shocked by Brown's emotion, explaining that she'd never seen him cry before.
"The adoption, there's a sense with the feeling that, you know, everything is so perfectly right," Brown explained in between tears.
"You know what, it was magical," Brown said of the experience. "It was just so, so surreal and I was spinning and it was like, 'Hey listen, there's two lottery tickets left and one of them's the million dollar winner,' and I'm just waiting for the other foot to drop."
Check out the full sneak peek of Brown's emotional moment below.
Despite Kody's obvious joy, his wife Meri was notably quiet.
Meri legally divorced Kody so that he could legally marry Robyn to adopt her children. Though the two insist they are still spiritually married, Meri was caught up in a catfishing scandal that has everyone wondering about the status of their relationship.
"I was dealing with a lot of other external issues during the whole filming of this season," Meri explained as to why she wasn't as present throughout the adoption. She agreed there was some detachment but "not because of the family."
She is, no doubt, alluding to her catfishing scandal and how that relationship unfolded in a surprising and hurtful way.
Sister Wives airs Sunday at 9/8c on TLC.
And you'll see personalized content just for you whenever you click the My Feed .
SheKnows is making some changes!