The policy,first developed under the Turnbull government,was rejected twice by the previous Senate but will be reintroduced when Parliament resumes after a six-week winter break.
More than 40 welfare groups,including the St Vincent de Paul Society and the Australian Council of Social Service (ACOSS),have condemned the measure in the past,with the Australian Medical Association saying it would increase stigmatisation among the most disadvantaged in the community.
The trials would be rolled out in Logan,south of Brisbane,Canterbury Bankstown in Sydney's south-west and Mandurah,south of Perth. A $10 million fund would boost drug treatment capacity in trial sites so job seekers who tested positive could access case management services.
The measures were previously opposed by Labor and the Greens,with the government expected to need four of the six crossbench senators to pass the bill.
One Nation's two senators and South Australian independent senator Cory Bernardi have previously supported the measures but Tasmanian independent Jacqui Lambie said she would back the trial only if all federal MPs were also prepared to be drug tested at work.
The government will dump its previous plan to charge job seekers who returned a positive drug test after concerns it would act as a punitive measure for those engaging with treatment.