The teenager managed to get up close to the Baby star and he kindly put an arm around her before she was dragged away by Irish singer Brian McFadden, who is a judge on the show.
Radevska subsequently told News.com.au, "I was looking around and saw a crack in security and thought 'Now or never.' He told me he loved me and it was all ok before I was dragged away."
It is not clear whether TV bosses plan to air footage of the incident during the TV talent show's grand final on Wednesday (18Jul12).
The show's host Grant Denyer, who was interviewing Bieber at the time of the stage invasion, hinted at the trouble in a post on his Twitter.com page, writing, "Daaaaaamn (sic)... that was absolute insanity! Scary but totally awesome! Justin Bieber caused pure mayhem... I'm deaf."