Health Minister Greg Hunt will today announce a $25 million overhaul Mandurah's Peel Health Campus - the biggest upgrade of the facility since it was opened over two decades ago.
The hospital has been the centre of a long-running campaign for more resources by Canning MP Andrew Hastie and state Dawesville MP Zak Kirkup.
Mr Hunt said $21 million would be spent on an expansion of the emergency department, the construction of a new Community Mental Health facility and a refurbishment of the medical imaging department.
A residential eating disorder treatment centre would be built at a cost of $4 million.
The population of Mandurah has doubled since the Peel Health Campus was commissioned in 1997.
Every month, 1100 operations are performed at the hospital and 1200 babies are delivered each year.
The emergency department deals with 45,000 visits per annum.
Last year state Health Minister Roger Cook announced $5 million to redesign the emergency department.
Mr Hastie and Mr Kirkup collected more than 1000 signatures from locals petitioning to upgrade the hospital and printed yard signs for residents call for more resources.
"Andrew Hastie and the Mandurah community led a strong campaign last year calling for better services at the Peel Health Campus," Mr Hunt said.
"They shone a light on an important local issue and the Liberal National Government is taking action.
"This $25 million investment demonstrates our commitment to improving health services throughout Australia and to building a world class health system."
Mr Hastie said the announcement was a vindication of the local community's efforts.
"Today is a victory for the people of Mandurah," he said.
"In May last year hundreds of local people joined member for Dawesville Zak Kirkup and I at a rally where we called on the WA Government to properly fund the Peel Health Campus.
"We have kept up the pressure on the state government since the rally, because as everyone in Mandurah knows, we need a better hospital. For over 280 days since, hundreds of local people have signed our petitions, written letters and put up yard signs, all calling for a better deal for PHC."
Mr Kirkup said the hospital was too small, under-resourced and desperately needed investment to expand the emergency department.
"The importance of this announcement by Andrew Hastie and Greg Hunt cannot be underestimated," he said.
"It wouldn't have happened without us all working together in Mandurah to take a stand and fight to a better local hospital.
"Andrew Hastie, Greg Hunt and the Liberal Party have listened to us, they have delivered for us and should be congratulated for what is an historic investment in our hospital."
The news comes after a 42-year-old Halls Head mother had a heart attack after she was sent home from the campus complaining of neck, back and jaw pain last year.
Mandii Tennick said she was made to wait for about 30 minutes before she asked a staff member to be seen because of her pain.
Another Mandurah mother said she was left waiting in the emergency room in urine-soaked pants for nearly an hour when she was taken to the campus in 2017.
A Peel Health Campus spokesperson said they were sorry for the issues Ms Foster experienced at the hospital.
"At the time of her attendance to the emergency department, it was an extremely busy time for Peel Health Campus," the spokesperson said.
"However, once we realised her situation, the staff were responsive and very apologetic."
Staff at Peel Health Campus failed to notify Josephine Foster's daughter that she had been taken to hospital after being rushed by ambulance to the health campus
Federal Opposition Leader Bill Shorten announced last year a $10.9 million promise to refurbish Bentley hospital in the target seat of Swan and $154 million for a mental health unit at Joondalup Health Campus.
In April last year, the Federal Government announced the contibution of $158 million towards a Joondalup Health Campus redevelopment, $10.6 million for Osborne Park Hospital and $20 million for an upgrade to Royal Perth Hospital.
The federal election is expected in May, 2019.