The 26-year-old - who got down to a size two after coming in second place during the ninth season of the ABC competition - told Access Hollywood that her appearance on the show "changed [her] life".
"[Former dance partner] Louis van Amstel and Dancing With The Stars changed my life, and as cheesy and cliché as that sounds, America had a hugest part in that," she explained.
"By picking up the phone and voting for me every week, and all the amazing things they said, [they] gave me the confidence to keep going at something that I was so scared and so terrified to do."
Osbourne went on to reveal that the reality of her accomplishment only became apparent after she posed in a bikini for an upcoming issue of Shape magazine.
"It was a bit of an emotional rollercoaster because I never thought that would be me or I'd ever look like that," she said.