The Oscar- and Grammy-winning performer – looking super slim in a black top and black jeans – took the stage to sing "Inseparable" with finalist Candice Glover.
Though Hudson, who was shockingly eliminated from the top seven of season 3, belted out high note after glorious high note, she let Candice, 23, have her a moment in the spotlight at the end of the song when she stood back and said, "Sing it, Candice."
And sing it she did! Candice held her own, hitting the final notes of the Natalie Cole song.
The judges ate it up – and were out of their seats in a standing ovation.
Host Ryan Seacrest summed it up: "Moments like that," he said.