Called Green Spine, the tallest of the projects's twinned towers will reach 356.2 metres high making it the tallest building in Australia.
The skyscraper will be topped by a publicly accessible botanic garden and greenery will burst through the facing facades of both towers as they twist towards each other.
"We will do our utmost to contribute to a healthier and future-proof Southbank and wider Melbourne with our Green Spine," said UNStudio co-founder Caroline Bos.
Dutch architects UNstudio and Australian firm Cox Architecture saw off competition from several other well known studios, including BIG, MAD, OMA and MVRDV, to design the £1.1 billion landmark development for Beulah International.
The taller of the two towers will be residential, with the 252.2-metre-high tower opposite housing offices, a hotel, restaurants and bars.
UNStudio and Cox Architecture designed the skyscrapers to have green spines that rise from the ground to the top of both towers.
These spine will feature greenery and outdoor spaces realised in natural materials, while the towers other glazed facades will punctuated by french balconies towards the base, transitioning to shading fins as the building rises.
"In addition to providing the towers with a twisting, sculptural silhouette, the Green Spine is an architectural element that incorporates a multitude of functions in one fluid gesture," said UNstudio founder Ben van Berkel.
A podium connecting the two buildings will contain a school, daycare centre, library, cinema, auditorium and a BMW experience centre. This podium will be topped by a publicly accessible terraced park.
Green Spine will stand more than 30 metres higher than Australia's tallest building – the 322.5-metre high Q1 tower in Gold Coast, and 50 metres higher than the Eureka Tower – Melbourne's current tallest building.
In Sydney, Ingenhoven Architects and Architectus recently won a competition to design a 79-storey skyscraper that will be the city's tallest building.
Images by Norm Li.
Client: Beulah International
UNStudio team: Ben van Berkel, Caroline Bos with Jan Schellhoff, Sander Versluis, Milena Stopic and Julia Gottstein, Marco Cimenti, Leon Hansmann, Perrine Planche, Olga Kovrikova, Carleigh Shannon
Executive architect: COX
Cultural placemaking: Future City
Lead artist: Studio Drift
Sustainability and well-being: Atelier 10
Landscape Architect: Grant Associates
Traffic & Accessibility: GTA Consultants
Visualisations: Norm Li