Migrant workers at a Sydney factory were denied overtime, Sunday and public holiday pay, resulting in staff losing out on hundreds of thousands of dollars.
Factory operator Winit was fined $550,000 on Wednesday after a court found the underpayments were "deliberate and systematic".
The Federal Court ruled in favour of the Fair Work Ombudsman on all the allegations it levelled against the Chinese-backed company.
The court found Winit underpaid 30 employees a combined $368,684 between July 2017 and June 2018, a sum the company had since handed over.
When the underpayments were initially revealed, the company tried to undermine claims against it by offering written agreements to pay employees far less than their entitlements.
Those who did not agree had their hours cut as a result, the company later admitted.
Winit's general manager and sole director at the time, Song Cheng, was also fined $8190 for knowingly underpaying workers.
"It is apparent that, despite being aware of the award and the obligations that it imposed, Mr Cheng instead determined that Winit should not meet them," Justice John Snaden said in the ruling.
He said the workers were mostly migrants on temporary visas and few would have been aware of their protections and entitlements under Australian laws.
Justice Snaden added the underpayments likely extended beyond the scope of the legal action, with internal audits by Winit suggesting between 2014 and 2019 it short-changed 400 employees by more than $3.6 million.
Winit has since taken steps to contact those employees and pay them what they are owed.
Justice Snaden noted the company, which was financially backed by its Chinese parent company, "does not appear to want greatly for funds when they are needed".
The company, which admitted all of the allegations against it, provides storage and distribution services for merchants selling products online through platforms like eBay.
