But a High Court ruling on Wednesday in favour of the airline could be undone by future federal legislation.
The airline is appealing two rulings by the Federal Court, which found the outsourcing of baggage handlers, cleaners and ground staff was illegal.
Transport Workers Union National Secretary Michael Kaine said workers might be owed compensation if the court rules against Qantas.
"If they weren't supposed to have been sacked under the law, then they had an entitlement to continue working and of course, that means they had an entitlement pay and conditions," he told Sky News.
Qantas was found to have breached the Fair Work Act in outsourcing its ground operations to avoid enterprise bargaining rights, after the Transport Workers' Union took legal action against the carrier.
The airline, which retrenched workers in 2020, lost billions of dollars due to the pandemic, which decimated the aviation sector.
Justin Gleeson SC for Qantas, told the High Court in May the airline's revenue stream had been shattered by the pandemic which left it "bleeding cash".
But the airline has since posted an underlying profit of almost $2.5 billion in the past financial year.
Qantas argued it could not have breached the workplace rights of the employees, as they did not have the right to take protected industrial action at the time of the decision to outsource.
Workplace Relations Minister Tony Burke has intervened in the case.
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