A donor to former Mayor Bill de Blasio convicted in a multi-million dollar bribery scheme had his sentence overturned Wednesday because of a Manhattan federal judge’s potential conflict of interest in the case.

A federal appeals court granted Jona Rechnitz’s bid to scrap both his five-month prison term and order to pay $12 million in restitution over his role in a plot to bribe disgraced Big Apple jails union boss Norman Seabrook to get him to funnel $20 million in union money into a failing hedge fund.

The Second Circuit Court of Appeals agreed with Rechnitz that sentencing Judge Alvin Hellerstein should have recused himself from the case because of his close personal ties to an employee of the fund, Platinum Partners.

The staffer, Andrew Kaplan, is the son of the judge’s close personal friend who died over a decade ago.

“The judge not only had a close, near- paternal relationship with Kaplan, but he also advised Kaplan on how to proceed in his pending criminal case arising from the Platinum fraud,” the ruling from Wednesday reads.

Kaplan was also a defendant and cooperating witness in another case against other people involved in the Platinum Partners fraud — which Hellerstein had already recused himself from.

Hellerstein in December 2019 slapped Rechnitz with a 10-month sentence with half to be served in prison and the rest to be served in home confinement.

The judge also ordered that Rechnitz should be on the hook for $12 million restitution — or the remaining restitution of the $20 million stolen from the Correction Officers’ Benevolent Association.

The appeals court ruled Rechnitz will be re-sentenced, with a different judge doling out the punishment.

Rechnitz — who cooperated as a star prosecution witness at Seabrook’s trial — has not yet served any prison time as his sentence was put on holding pending the appeal.

Platinum Partners head Murray Huberfeld took a guilty plea in 2018 for ordering Rechnitz to bribe Seabrook and was sentenced to seven months in prison after a earlier sentence was overturned.

Rechnitz testified at at Seabrook’s trial about how he had handed him a $60,000 bribe in a leather Salvatore Ferragamo bag.

Seabrook was convicted at a 2018 trial after a prior 2017 trial against him ended with a hung jury. He was released from a federal lock up in March after serving a 22 months behind bars.

“We appreciate the panel’s thoughtful decision,” Rechnitz’ lawyer Noam Biale told The Post in an email statement. “Mr. Rechnitz provided exemplary cooperation and has done everything in his power to make amends. He looks forward to obtaining closure in this matter.”

The Manhattan US Attorney’s Office — which prosecuted the cases — declined to comment Wednesday.