The British designer - famed for her wedding dresses - made a bespoke champagne-coloured gown for the 17-year-old star to wear at this year's prestigious ceremony and was thrilled to see her in it.
She said: "The press results from an Oscar wear are incredible. Many designers pay stars to wear their dresses, however we try and create the best possible relationships with the artists and their stylists and hope that they fall in love with the designs of their own accord, like Miley did.
"She fell in love with a white dress from our spring/summer collection. She loves the softer Champagne colours so I created something especially for her. She is young, beautiful and talented and I was honoured to be asked to create her special dress for the biggest fashion event of the year."
Jenny was always confident Miley would wear the dress - which was clinched in at the waist with a sweeping floor-length skirt - because she had formed a close relationship with the singer-and-actress.
She told vogue.com: "Designers are often asked this question and the reality is, like you or I, Hollywood starlets can change their mind at any moment. I had worked for quite some time on creating this dress for her, and we had been sending Miley images of the dress as it had progressed from London to Los Angeles. We were confident she would wear it, as we all knew how beautiful she would look in it."