John Gotti’s grandson is finally behind bars for his long-delayed COVID-19 fraud scheme sentence after failing to donate his kidney to his sickly mother by a Brooklyn judge’s deadline.

Carmine Agnello, 40, self-surrendered on Aug. 10 and kicked off his 15-month sentence at the Federal Correctional Institution Fairton in New Jersey, according to the Federal Bureau of Prisons.

The grandson of the notorious Gambino crime head was initially ordered to start his sentence on June 20, but he got a two-month reprieve so he could undergo the organ transplant procedure for his mom, Victoria Gotti, on Aug. 3.

But that date came and went, and Agnello still had his kidney. He told the Brooklyn federal court that his mother was battling a severe infection and begged for yet another extension.

“It is nonetheless hoped that she will be cleared for surgery in the coming days and Mr. Agnello stands ready to provide the donation and simply awaits word of greenlight for surgery,” Agnello’s attorney Robert Beltrani wrote in a letter to Judge Nusrat Choudhury on Aug. 4.

Choudhury delivered an ultimatum in court on Aug. 6 — if the surgery occurred on or before Aug. 10, Agnello could enjoy one more month of freedom, until Sept. 18 rolled around.

If not, the former reality TV star was ordered to turn himself in on Aug. 10, according to the case’s docket.

Agnello begged yet again to delay his surrender date until Sept. 18, arguing that his mother is still battling a nasty infection so they couldn’t schedule the surgery in time.

“This is an unusual and deeply personal circumstance,” Beltrani wrote in a letter filed on the day Agnello turned himself in.

“Carmine is not asking the Court to interfere with his sentence or provide him with special treatment.”

But the motion was denied — the judge ruled that without any surgery on the books, Agnello couldn’t avoid his fate any longer.

“Because there is no concrete evidence that an organ transplant will be scheduled to take place at any time between today and September 18, 2026, the request for another deferral of Mr. Agnello’s self-surrender is unjustified,” the judge said, per the docket.

Prosecutors with the Brooklyn US Attorney’s Office have repeatedly argued that the situation did not warrant any leniency from the court and said that Agnello could give up the kidney while behind bars.

Agnello was sentenced on April 20 after pleading guilty to skimming Economic Injury Disaster Loans from the Small Business Administration that were meant to help companies recover from the pandemic shutdown.

He was also ordered to pay $1.2 million in restitution on top of his prison sentence.