The mother guided Kodi on stage for his performance and did most of the speaking when it was time to answer the judges' questions.
She told them music had literally saved Kodi's life and allowed him to have a happy existence in the world.
When he sat down in front of the piano, aided by his mum, no one expected to see what was about to happen.
Simon Cowell couldn't stop staring, his eyes looking a little watery, and Julianne Hough was wiping tears before the song was finished.
His mum knew he was talented but wasn't expecting him to conquer everyone quite that way.
"I've been watching him perform for quite a while, but that day on stage, the sound as he started to sing, it was like the best sound I have ever heard come out of his mouth," she told the NBC programme.
"Like, I was shocked. I literally could not stop crying. It's almost like he knew that was the place to like, give it all.
"He'd always say, 'I want to perform for thousands of people.' And I'm like, Kodi, you're performing for millions of people," she said.
"He's just such an innocent soul, and he's so happy, always. And to be around him, it helps you be happy."
Kodi said he's excited at all the attention he's getting since the show aired.
"I feel excited," he said, and when asked if he's also anticipating the live shows coming up, he said: "Heck yeah!"
According to Kodi's website, the 22-year-old was born with optic nerve hypoplasia, a congenital condition which means the optic nerve has not fully developed.
"Born with optic nerve hypoplasia, surviving a life-saving surgery at five days old, and being diagnosed with autism at an early age has never stopped Kodi from reaching for his dreams," his online bio says.
"Kodi continues to pursue his musical career and his dream is to be a "rock star" performing for thousands of fans.
"Any opportunity Kodi has to perform is a good day for him, and the bigger more energetic the audience, the more he loves to shine."
The judges all agreed Kodi's performance was one of the best they'd ever seen.
America's Got Talent newest judge, Gabrielle Union, pressed the coveted "golden buzzer" — using up her only opportunity to do so for the season — which automatically sent Kodi to the next round of the competition, in Hollywood.