An anti-slavery commissioner is needed to clamp down on corrupt and illegal business practices, according to the Australian Council of Trade Unions.
The Modern Slavery Bill is back in the Senate on Monday, where proposed amendments will be floated.
When the bill was last in the lower house in September, Labor's attempts to establish a commissioner and include penalties for non-compliance were voted down.
More than 40 million people worldwide are believed to be victims of modern slavery, including 4300 Australians.
Modern slavery covers issues such as forced labour, child labour, people trafficking, debt bondage and the sale or sexual exploitation of children.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
ACTU president Michele O'Neil says significant changes are needed to protect the rights of Australians.
"We call for changes to this bill that hold companies accountable for the presence of slavery in their supply chain and provide penalties for those companies that choose not to investigate and report," she said.
"If these changes come into place, companies will need to report what they have done to deal with slavery in their supply chains and they will face penalties if they do not.
"The appointment of an independent anti-slavery commissioner will ensure proper monitoring takes place, rather than having oversight of the scheme buried within Peter Dutton's department."
In June, the NSW Parliament became the first Australian state to pass a Modern Slavery Bill, which created the position of an anti-slavery commissioner.
The United Kingdom introduced the Modern Slavery Act in 2015, with reported cases doubling during the last year.
