Ghislaine Maxwell’s formal notice of appeal of her sex-trafficking conviction and 20-year prison sentence was made public Thursday — kicking off what likely will be a lengthy legal process.

Maxwell’s notice of appeal — the first step in a process that will likely last several months at the very least — was filed publicly nine days after her sentencing last week, during which she issued a half-hearted apology to her victims.

The British socialite was convicted in December by a federal jury on five charges and ordered to pay a $750,000 fine for her role in grooming young girls for her one-time boyfriend and pedophile Jeffrey Epstein.

At sentencing, Manhattan federal court Judge Alison Nathan said 240 months behind bars was “sufficient and not greater than necessary,” saying she caused “incalculable” damage to victims.

While Maxwell’s lawyers have long claimed she was being unjustly persecuted for Epstein’s crimes, the judge said Maxwell “is not being punished in place of Epstein,” emphasizing she “participated in a horrific scheme” and facilitated “sexual abuse by and with Jeffrey Epstein.”

Prosecutors asked Nathan to slap Maxwell with at least 30 and up to 55 years in prison, so that her punishment “sends a message that those who conspire with sexual predators will be held responsible for their significant role in these crimes.”

Maxwell’s team had begged for leniency, saying she should get no more than four to five years, while probation officials recommended 20.

The Oxford-educated heiress and daughter of late publishing tycoon Robert Maxwell — who spent much of her life hobnobbing with the rich and famous — was convicted of sex trafficking on Dec. 29, 2021.

Before her punishment was delivered, Maxwell acknowledged her friendship with the sick financier — who killed himself behind bars in August 2019 while awaiting trial on sex-trafficking charges — will “forever and permanently” stain her.

“I believe that Jeffrey Epstein was a manipulative, cunning and controlling man who lived a profoundly compartmentalized life and fooled all of those in his orbit,” she said.

“It is the greatest regret of my life that I ever met Jeffrey Epstein,” she said, calling him “manipulative, cunning and controlling” and saying he, “should have been here.”

“I hope my conviction and harsh incarceration brings you closure,” she added.

Maxwell could remain behind bars until her late 70s, with possible credit for good behavior plus credit for the two years she has been jailed at Brooklyn’s Metropolitan Detention Center.

With Post wires