The United Workers Union says Monday's action follows a similar walk-out in May amid demands for a fair wage increase.
NT Secretary Erina Early said the industrial action would continue to escalate until the government returned to the negotiating table with a reasonable offer.
Wage negotiations started in mid-2021 with workers demanding a three or more per cent annual pay rise to keep pace with cost-of-living increases.
"Corrections continue to be at crisis levels with overcrowding, lack of staff, an inadequate budget," Ms Early said.
"Correctional officers are suffering and we need to ensure they are properly remunerated for the risk they deal with on a daily basis.
"I urge the government to consider the long-term impacts of their four-year wage freeze."
The pay freeze for more than 20,000 public servants was introduced in November 2020 in a bid to save more than $400 million amid ongoing Territory government deficits and climbing debt levels.
It was accepted by 57 per cent of employees.
In May this year, dozens of prison guards in both Alice Springs and Darwin walked off the job also calling for an end to the freeze and as well as protesting the alleged under-resourcing of the sector.
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