Construction of one of the State’s biggest residential developments worth $138 million — and boasting WA’s most expensive penthouse — will begin next month in Subiaco.

Site preparations are already under way for the 245-apartment ONE Subiaco tower complex across three buildings on Rokeby Road, the highest reaching 24 storeys with views over the city, the hills and Rottnest Island.

Multiplex will start the mammoth project on September 18 — due for completion in late 2022 — after being awarded the lucrative build by developer Paul Blackburne.

Multiplex managing director Chris Palandri confirmed it would be one of the largest mixed-use projects under construction in Perth for many years to come.

Mr Blackburne said more than 80 per cent of the apartments, worth about $200 million, had sold off the plan, defying expectations amid one of the toughest economic cycles in history.

He claimed this included a $17 million penthouse, which sets a new record for most expensive apartment in WA.

He said there was potential to add another $17 million penthouse to the design but it had not yet sold.

Mr Blackburne expects most of the remaining $80 million worth of apartments would sell over the next month.

“ONE Subiaco is an important project for WA, it will provide a stunning symbol of the strength of the local market for larger high-end apartments and create up to 1100 jobs during construction,” he said.

“The success of ONE Subiaco shows continued strong demand for larger higher-end apartments in Perth despite recent national and global events.”

The project will be one of several set to breathe life back into the inner-city area, which has struggled since West Coast stopped playing at Subiaco Oval in 2017.

The complex will include 14 new shops including seven cafes, bars and restaurants.

A market place will open on completion, returning a fresh fruit and vegetable market to the site which was once home to the Pavilion markets. The complex will also include four retail outlets, and office space on the first floor.