Courtney presented herself as a shy, quiet and nervous girl onstage, with her father admitting backstage she has trouble socializing with people outside of her family, especially kids at school.
Courtney did reveal, however, her favorite subject in school is music, and then she started singing.
Courtney belted out Otis Redding's "Hard to Handle," which was a song covered in the '90s by the Black Crowes.
The sweet and petite British teen shocked everyone when she began rocking the stage with her quirky dance moves and passion exuding from her expressive face.
"Bloody hell Courtney," enthused Simon. "You were this shy little thing when you came out. Then you sing and you're like a lion. I mean, genuinely incredible."
Howie subsequently gushed, "Oh my gosh. You are not from this era. You are from a whole different era."
After comparing Courtney to Janis Joplin and how she was discovered by chance on a normal, average day, Howie continued, "I can't sign you to a record deal. The only thing I can do for you young lady is give you..."
Howie then hit the golden buzzer as Courtney cried tears of joy on the stage and golden confetti fell from the ceiling.