Casino giant Crown will expand its Southbank site to eight hectares after it won approval from the Andrews government to build a $1.75 billion 90-storey tower.

Once completed it will be Melbourne's tallest building, at 322 metres, exceeding Eureka Tower by 25 metres.

The 1 Queensbridge Street site will be home to a 6-star hotel with 388 rooms and 708 apartments.

Premier Daniel Andrews said the project was of "state significance" because it would create 4000 jobs; 3000 during construction and another 1000 once up and running.