Child sex abuse survivor Kirsty Pratt has long campaigned for WA to remove the time limit for victims to seek compensation and says laws introduced by Labor will eliminate that "barrier to justice".
The bill also provides a legal basis for suing institutions in the name of their current office holders for historical cases and ensures victims are treated fairly by introducing a cap on legal fees.
Ms Pratt held back tears on Wednesday and said it was a "no-brainer" that the bill should pass.
"This is the removal of a barrier to justice," she told reporters.
"This is also an opportunity for many who have not been able to get some acknowledgement for the sheer devastation that has been placed on our lives and an opportunity to heal some wounds."
Attorney-General John Quigley said the government was delivering on its election commitment but conceded it had taken longer than expected.
He could not estimate how many people might seek civil action but said it would probably cost hundreds of millions of dollar over years.
"You can't put a price on justice ... these people who have had their lives destroyed need justice, they need their day in court and they need their proper compensation."
Mr Quigley said if a victim had already received redress, it would be deducted from their compensation.
Ms Pratt also defended the cost and said in other jurisdictions where similar legislation had passed there was not a "flood of claims" as feared, although she conceded the WA proposal was broader than other states'.
Premier Mark McGowan said on average it took a person 22 years to disclose child sex abuse, so the current limitation period of six years was clearly unacceptable.
"Often, they're too traumatised within the limitation period to be able to seek justice (but under this bill) you will have the opportunity to pursue those perpetrators - those people or those organisations responsible - forever."
Maurice Blackburn Lawyers principal Phil Gleeson said while WA was one of the last states to lift the time limits for abuse survivors, it was now setting a new benchmark.
Last year, when Labor was in opposition, a private members bill introduced by Liberal MP Graham Jacobs failed but both sides of politics indicated they wanted to pass the law in some form after the March election.
