The 'Applause' hitmaker stood out on the red carpet at the Dolby Theater in Los Angeles in her white crystal-embellished gown, which she'd accessorised with red gloves.
And she took to her Instagram account on Sunday evening to share with her fans how long the stunning dress took to make.
She wrote alongside a photograph of her on the red carpet.
"I will never forget tonight. #Oscars thank you Azzedine Alaia for this stunning piece. It took 1600 hrs of embroidery and 25 people in Paris, he's never before made a dress for the Oscars.
The 28-year-old singer, who got engaged to her beau Taylor Kinney on Valentine's Day , took to the stage at the glamorous ceremony to perform a medley from 'The Sound of Music'.