Attorney-General and Industrial Relations Minister Christian Porter said there are many Australians still out of work, or doing fewer hours as a result of the COVID-19 pandemic.
"We cannot do nothing when we have a situation where employers are delaying making hiring decisions because of ongoing confusion about the legal status of casual employment," Mr Porter said.
Labor industrial relations spokesman Tony Burke urged people to be wary of suggestions the proposed laws would be good for casuals.
Mr Burke said casuals will lose workplace rights if employers are able to abuse their conditions without consequences.
"Labor still hasn't seen the legislation but when you look closely at the reports it seems this is another example where the spin of the government announcement is the opposite of the delivery," he said.
The legislation to be introduced on Wednesday will cover three areas.
It will introduce the statutory definition of casual employment in the Fair Work Act, which will include employment being offered without any firm advance commitment that the work will continue indefinitely and follow an agreed pattern of work.
"Our definition of casual employment is likely broader than some business groups had wanted," Mr Porter said.
"Unions are likely to say we should have made the definition broader still, suggesting to me that we have struck the right balance on this issue and delivered a fair and equitable outcome that will benefit both workers and employers."
The legislation will address the so-called "double-dipping" issue where currently employers may have to pay for sick leave and other leave as well as the 25 per cent casual loading meant to compensate for those benefits.
The government will ensure employers do not have to pay worker entitlements twice by legislating to ensure that a court deducts any identifiable casual loading paid to compensate the employee for the absence of one or more entitlements.
But Labor is concerned bosses could be the ones double-dipping.
"If an employer tries to take the reliability of a permanent roster but only offers the insecurity of casual work, it's the employer who is double-dipping," Mr Burke said.
The government proposal would overturn the current cases which had protected workers where labour hire was causing casual workers to be paid less than the permanent workers doing the exact same job.
The new laws will also create a new minimum standard for casual conversion so that casuals who work regular shift patterns can move - if desired - to part-time or full-time employment after 12 months.
"These are significant reforms which together will solve the problem of uncertainty, provide better avenues for job security, remove the burden of double-dipping claims and recognise employee choice," Mr Porter said.