Walker and the South Australian Government have unveiled a plan to revamp the Festival Centre precint in Adelaide with the development of a new Festival Plaza, at a cost of A$600m.
Festival Plaza will combine entertainment and commercial amenities for locals and tourists.
According to the company, the A$1bn project will feature a multi-purpose 5,000m² city square, a 40,000m² premium office complex behind old Parliament House, as well as a two-storey podium precinct with cafés, restaurants and retail outlets.
As part of upgrade, the existing, dilapidated 300-bay facility will be replaced with a 1,500-bay carpark, including 400 spaces for the exclusive use of parliament staff and a further 750 leased to the casino to support its re-development.
The city centre would be integrated with amenities such as the Adelaide Oval, Adelaide railway, the casino, Festival Centre and convention centre.
Walker chairman Lang Walker said: "We will be breathing life back into the Riverside area, which has laid dormant since Don Dunstan's premiership in the 1970s, with a project that will become one of the world's best and most exciting public spaces.
"I congratulate the South Australian Government for its commitment to activate the space, ensuring the people of Adelaide get a great outcome for a tired and under-utilised public domain.
"The development will provide a new heart for the city, with the square to be designed to be flexible and accommodate concerts, exhibitions, pop-up food and beverage stands, art and other cultural exhibitions."
Expected to start this year and be completed in early 2018, the project will also separate vehicle and pedestrian avenues to improve traffic flows.