Mike Bloomberg’s big-bucks presidential campaign is even putting prisoners to work.

The Bloomberg campaign admitted that it inadvertently used inmates at an Oklahoma prison to make calls on his behalf through an arrangement made by one of its vendors.

The Bloomberg camp contracted New Jersey-based call center company ProCom, which runs call centers in Jersey and Oklahoma.

Two of the call centers in Oklahoma are operated out of state prisons, according to a report published on The Intercept.

A source told the website that inmates at one of the two prisons — the Dr. Eddie Warrior Correctional Center, a 900-inmate, minimum-security facility for women — made phone calls to California on behalf of billionaire Bloomberg, the former three-term New York City mayor who launched a late entry into the presidential primary last month.

The female inmates disclosed at the end of the phone interviews that the calls were paid for by the Bloomberg 2020 campaign — but did not identify themselves as convicts calling from behind bars.

The Bloomberg campaign fessed up to the goof after claiming it was not aware it was paying prisoners to make phone calls.

“We didn’t know about this and we never would have allowed it if we had,” said Bloomberg campaign spokeswoman Julie Wood.

“We don’t believe in this practice and we’ve now ended our relationship with the subcontractor in question,” she said.

The revelation drew criticism from inmate advocates that the calls made for Bloomberg smacked of the exploitation of prison labor.

It’s unclear precisely how much the inmates were paid for aiding Bloomberg. A ProCom official told The Intercept it pays inmates the minimum wage of $7.25 in Oklahoma, though the state prison system lists a cap on how much inmates can make per month.