Lee, who is blind and has autism, stunned the crowd with a flawless cover of Donny Hathaway's "A Song For You."
The 22-year-old contestant was accompanied on stage by his mom, who gave him a pep talk before he shocked the judges and crowd with his voice and piano playing skills.
"We found out that he loved music really early on," Lee's mom, Tina, told the crowd. "Through music and performing, he was able to withstand living in this world. Because when you're autistic, it's really hard to do what everyone else does. It actually has saved his life, playing music."
Judge Julianne Hough wiped away tears as she praised his performance. Fellow judge Howie Mandel told Lee, "I heard you, I felt you and it was beautiful." Simon Cowell called the performance "extraordinary."
Gabrielle Union saved the best for last, slamming down on the golden buzzer for Lee, the first of the 2019 season and advancing Lee straight to the finals.