The man was working at Golden Plains Wind Farm in Rokewood, west of Melbourne, when he was crushed by the rotor blade on Monday morning, Victoria Police said.
"First responders attempted to revive the man, but he was declared deceased at the scene," police said in a statement.
The Golden Plains Wind Farm is owned by TagEnergy and Ingka Group and consists of two sites, West and East, where the accident has occurred and construction has been underway since early 2023.
Vestas, the company building the project, confirmed the incident.
"The site has been closed and we are working closely with emergency services and the authorities," the organisation said in a statement.
The rotor blades used in the project are roughly more than 80 metres in length, according to the organisation's website.
Three unions, the Australian Workers Union, CFMEU and Electrical Trades Union, had warned Vestas of safety concerns in the weeks leading up to the event, Australian Workers Union state secretary Ronnie Hayden said.
"This devastating loss could have been prevented," Mr Hayden said.
"Just two weeks ago, union delegates from three different unions met with Vestas management to raise serious safety concerns, telling them it was only dumb luck that nobody had been killed on site yet."
The union accused Vestas of transferring safety obligations onto subcontractors who lacked the necessary training.
"This is not just another statistic, this is a worker who went to work and never came home," Mr Hayden said.
"We need more than just investigations and reports, we need immediate action on site safety and stronger enforcement of regulations."
Speaking at a press conference in Melbourne, Victoria's premier Jacinta Allan expressed her sympathies and noted the state had strong workplace safety regulations.
"Any accident in any workplace is indeed a deep concern and a tragedy," Ms Allan said.
Once completed, the project will be the biggest wind farm in the southern hemisphere, producing more than 4000 gigawatt hours of energy each year, about nine per cent of the state's current energy demand.
The project's first turbines were connected to the grid in October in a launch by state Energy Minster Lily D'Ambrosio.
View this post on Instagram A post shared by Lily D'Ambrosio (@lilydambrosiomp)
The wind farm has planning approval for up to 228 turbines, the current design comprising 215 turbines across 16,739 hectares.
The incident came after another wind farm worker was killed in April after falling 20 metres from a wind monitoring tower at a site in Queensland.
WorkSafe is investigating and police will prepare a coroner's report.
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