Olivia Creighton, 24, of Worsbrough Common, had originally designed the dress as part of her graduate portfolio - and she admits she never expected it to be on the shoulders of the pop star.
She told the Chronicle: “I got an email while I was on holiday with my friends in Cornwall asking if I could send the dress over to a stylist because he was getting together some looks for Ellie to try.
“Someone sent it over for me because I wasn’t home and from there I didn’t think much of it because I thought she’d have lots of options from high-end designers and mine wouldn’t be picked.
“I checked on her Instagram on the day and I saw she was wearing it and I was really overwhelmed - it’s a dream come true.”
It’s been a whirlwind of a month for the former Sheffield Hallam University student as she also picked up the award for the best digital portfolio at Graduate Fashion Week, held in London.