It is hoped the new facilities, which include a multi-purpose centre for a range of recreational activities and an extended laundry, will give more purposeful activity to inmates.

A 2015 auditor-general's report found prisoners were active for five hours a week, and only two in five detainees were being put to work, and slammed the failure to create a structured day, considered crucial to rehabilitation.

This fell far short of the government's goal before the prison opened to have inmates active six hours a day, 30 hours a week.

When the new facilities were launched on Friday, executive director at ACT Corrective Services Don Taylor said 188 of the prison's 430 detainees employees were now in full-time work and 66 were in full-time rehabilitation or education programs.

And he said the expansion had opened up a further 30 positions with much more variety, with the multi-purpose centre and bakery each opening up 14 full-time jobs.

"The new gym is a wonderful expansion for vocational capabilities and training of detainees that may assist them once they leave the centre," Mr Taylor said.

"We have two full-time staff members certified in fitness and will allow that to go onto detainees as well."

Mr Taylor said inmates were undergoing about 5000 haircuts a year and the new hairdressers would provide opportunities for them to assist with cuts.

Meanwhile, the extended laundry would tripled capacity from 76kg to 225kg.

Before its opening in 2008, the jail aimed to be human rights-compliant and to focus on rehabilitation to minimise reoffending.

But combining a variety of prisoner types and all genders in a small facility caused overcrowding problems, and struggles juggling detainee association issues.

Mr Taylor said the new facilities, particularly the multi-purpose centre, would allow for different activities to be undertaken at once, minimising movement and interactions between problem groups.

ACT Corrections Minister Shane Rattenbury admitted the jail had struggled in recent times but was confident the new expansion, as well as the construction of new cells earlier this year, would ease pressure off staff and help better manage separation.

"It means we have physical facilities we need and can focus on rehabilitation," Mr Rattenbury said.

"We hope to expand industries further into the future, and while it's about getting the right industries inside the jail, we also have to make sure that what we do in here won't compete with businesses outside the jail in the community."

An ABS snapshot from June 30 this year shows there has been an 11 per cent increase, 45 prisoners, to the adult prison population in the ACT since 2015.

But the territory has the largest proportion of recidivist prisoners of any state or territory.

Nearly three-quarters of prisoners, 74 per cent or 324 prisoners, had previously been imprisoned under sentence, compared with the national average of 56 per cent.

The median age of adult prisoners was 34 years old. Ninety-four per cent of the total prisoner population was male and 24 per cent of prisoners were Aboriginal and Torres Strait Islanders.

The Aboriginal and Torres Strait Islander age-standardised imprisonment rate was 18 times the non-Indigenous age-standardised imprisonment rate.

27 per cent of prisoners, 120 people, were charged with acts of intending to cause injury making it the most common offence, followed by 12 per cent of prisoners, 51 people, charged with sexual assault.

The median aggregate sentence length for sentenced prisoners was 2.5 years but 32 per cent of the current population at the time of the snapshot were unsentenced.