Legislation introducing a 90-day work trial for all new employees has been passed in Parliament.
Previously, the trial period applied only to companies with fewer than 20 staff.
Now, all new employees can be sacked without reason within the first three months on the job.
The National Party argues the change will create more jobs.
The Labour Party has been particularly critical of the fact sacked employees cannot challenge their dismissal.
The Maori Party also opposed the bill, saying it weakens the position of Maori in the workplace.