A class action launched against McDonald's alleges 25,000 people were not paid for work done before and after their rostered shift times.
An estimated 25,000 McDonald's workers could take part in a class action against the fast food giant that is seeking millions of dollars in alleged unpaid overtime.
The restaurant chain and franchisees are accused of failing to pay managers and supervisors up to an hour of unpaid work each day as they performed checks and handovers outside their rostered shift times.
A statement of claim has been filed in the Federal Court by the Shop, Distributive and Allied Employees' Association.
The union believes the total amount owed could be more than $100 million and is also calling on the court to financially penalise McDonald's Australia.
It applies to all shift supervisors, department managers, assistant restaurant managers and restaurant managers who worked at the chain over the last six years.
The union's national secretary Gerard Dwyer claimed it was wage theft and exploitation on a colossal scale.
"McDonald's is operating on a broken business model," Mr Dwyer said.
"As one of the country's largest employers, McDonald's should not be requiring managers to work up to one hour per shift without pay."
Former McDonald's shift supervisor and department manager Mikayla Martin-Coats said she was constantly told to get to work 30 minutes early during her three years as a manager but felt powerless to do anything about it.
"If I didn't get to work 30 minutes early, I would be called in for a meeting and receive a warning from my manager, it wasn't worth risking getting there on time," she explained.
"There was a long list of tasks that I was required to do before every shift to ensure everything was ready to go and the store was up to standard."
A spokesperson for McDonalds Australia said it is committed to ensuring workers receive correct entitlements and pay under the relevant award and a former enterprise agreement.
"McDonald's Australia takes its obligations under all applicable employment laws very seriously," they said.
"We value our people and the contributions they make to our restaurants every day."