Around 300 part-time cleaners will be directly employed by the government from the end of January next year.

The cleaners are currently employed by four companies, who between them hold eight contracts for the ACT's 87 public schools.

Previously 23 companies cleaned the territory's schools, but allegations of underpayment and sham contracting forced the government to condense the contracts and to introduce six-monthly audits on compliance with industrial relations and safety laws in 2017.

Now Education Minister Yvette Berry said it had become clear the ACT government's "high standards for ethical, industrially-compliant employment" were unlikely to be met through an outsourced service.

"Achieving these high standards is difficult in the cleaning industry, where margins are tight and the services are homogeneous. The required contract management has also proven very demanding," Ms Berry said.

Ms Berry said the rates of pay and conditions for school cleaners would be "broadly comparable" to what they were currently on.

"There are modest additional costs associated with insourcing, largely to support enhanced quality systems and work, health and safety practices," she said.

But Ms Berry said Labor had made an election commitment to improve the treatment of vulnerable workers.

"For example, a large number of these [cleaners] are from the S'gaw Karen people group and now live in Canberra after fleeing conflict in Myanmar," she said.

United Voice ACT secretary Lyndal Ryan said the decision was an historic one because, unlike in other states, cleaners had never been directly employed by government in the ACT.

The union had lobbied for years for cleaners to be directly employed by government, saying it would provide better job security and conditions.

"They were being treated like second class citizens when in fact they were providing essential services like everybody else," Ms Ryan said.

"No matter what was done with procurement to make jobs more secure, the reality is contracts have termination dates. Every three years you don't know if you have a job. This decision changes all that."

Ms Ryan said while it would be more expensive to bring the cleaners in-house, there would also be cost savings from not having to shift contracts every few years.

It would also mean cleaners could be deployed where needed without requiring a contract variation.

But for Karen Love, the decision to directly hire means much-desired permanency.

The grandmother has worked as a cleaner at Macquarie Primary School for more than a decade under two different companies.

"When mum passed away I was entitled to bereavement leave and the boss told me if I took it I would be fired," Ms Love said.

"When I got back he was showing a lady around to take over my job, he said if I ever took leave like that again she'd have my job.

"I love my school and didn't want to leave it. The teachers have invited me to their Christmas party, I go to their baby showers. For the last seven years, the year six students have invited me to their formal.

"I always felt like I was a part of the school, now I'll officially be part of it. That means everything to me."