Brown was forced to withdraw from the panel of the hit show due to a legal challenge from her former employees at rival Australian reality Tv show The X Factor, and Halliwell has now been announced as her replacement.
The singer admits Brown encouraged her to make the life-changing decision to move Down Under.
In a post on her Twitter.com page, Halliwell writes, "Mel B encouraging true friend - told me to go for it."
She adds, "She actually said 'I just want you to know I think you should do it cause you're gonna have a great time and I love Australia'... I actually genuinely love the show, you know. I watch Britain's Got Talent and I'm a fan of the show. I think shows like that are brilliant and I love the opportunity they give to normal, everyday people.''
A statement from Tv bosses behind the programme reads, "Look at her... Got Talent AU's 4th Judge is Geri Halliwell!"
The move will mark a return to reality Tv competitions for Halliwell, who previously worked as a judge on 2002 U.K. series Popstars: The Rivals - the show which created pop group Girls Aloud.