Billionaire Alex Waislitz has signed off a blockbuster settlement with his Australian heiress ex-wife to end a furious row over secret millions, luxury mansions and his glamorous popstar girlfriend.

The multimillion-dollar deal with Heloise Pratt, daughter of the late cardboard king Richard Pratt, means a simmering dispute centring on Waislitz's much younger fiancée Rebekah Behbahani is no longer headed for a Supreme Court trial.

The agreement with Mr Waislitz, whose tech investment company has more than $1.3billion in net assets, comes after a year of legal wrangling.

Mr Waislitz, 67, was accused of funding the music career and extravagant lifestyle of Behbahani, 35, who is mother to his daughter, Storm Behbahani-Waislitz.

He denied claims he took secret loans from a shared trust with his ex-wife or that he tapped their company Tiga Trading and subsidiaries for $1.23million to fund the purchase of two Melbourne townhouses without her knowledge.

Rebekah Behbahani and her sister Venus Behbahani-Clark, the former Real Housewives of Melbourne star, were also reported to have been living rent-free in Toorak, one of Australia's wealthiest suburbs.

The Persian-born sisters were embroiled in their own court battle two years ago when Behbahani-Clark took a civil action in the Supreme Court of Victoria, claiming she was given one of the townhouses during a short separation between her sister and Waislitz.

Behbahani-Clark claimed she moved into the home with partner James Clark and their children in 2019, and had been given the home via a 'deed of gift' from her sister.

Billionaire Alex Waislitz and his fiancée and baby mother Rebekah Behbahani (above) were the centre of acrimonious allegations by his ex-wife, packaging heiress Heloise Pratt, but the matter has now been dropped in a multimillion-dollar settlement   

Packaging heiress Heloise Pratt and her now ex-husband, investment billionaire Alex Waislitz, pictured together in 2010, separated in 2015

Mr Waislitz's fiancée Rebekah Behbahani (left) and her sister Venus (right) fell out briefly fell out over a dispute about living in luxury Toorak properties rent-free

Mr Waislitz's Thorney Investment Group then launched a counterclaim seeking to evict the family from the house.

Over the last year, Mr Waislitz and Ms Pratt have been embroiled in a struggle for control of Thorney. 

The company was founded in 1991 after Visy packaging mogul Richard Pratt gave his future son-in-law shares worth $1.2million in global paper manufacturing giant Amcor. 

Within a decade, Mr Waislitz had grown the portfolio to an estimated $300million, now believed to be worth up to $1.5billion.