In a Wednesday night court filing, prosecutors said denying the 81-year-old Madoff's request would uphold victims' and public faith in the justice system.
They said Madoff should continue serving his 150-year sentence, to ensure that "one of history's worst fraudsters" faces the consequences of his crimes.
"Madoff's crimes were extraordinarily evil," prosecutors said. "His sentence was appropriately long. It should not be reduced."
Prosecutors also said roughly 500 of the 520 victims who wrote to the Manhattan federal court about Madoff's request opposed it, including an 84-year-old who said: "Why should he be shown any compassion, when he had none for his many victims?"
The filing came one month after Madoff sought "compassionate release," saying he had fewer than 18 months to live and hoped to move in with a friend.
"Madoff, despite what the government might claim, is remorseful for his conduct," and "remains hopeful" his request will be granted, his lawyer Brandon Sample said in an email.
Madoff has spent roughly 10-3/4 years in prison.
His case is the biggest test of the First Step Act, a bipartisan law signed by President Donald Trump in December 2018 affording early freedom to some older prisoners, often for health reasons.
Among those released is Bernard Ebbers, who once led phone company WorldCom Inc. He died on Feb. 2 at age 78.
Prosecutors said Madoff used his firm Bernard L. Madoff Investment Securities LLC to swindle thousands of individuals, charities, pension funds and hedge funds, including many with ties to the Jewish community.
A court-appointed trustee estimated Madoff's customers lost $17.5 billion. Nearly $14 billion has been recovered.
Madoff was arrested in December 2008 after admitting his fraud to his sons, who have since died, and pleaded guilty three months later to 11 criminal counts.
His fate will be determined by Circuit Judge Denny Chin, who called Madoff's crimes "extraordinarily evil" when imposing the 150-year sentence in June 2009.
In seeking Madoff's release, Sample said his client is confined to a wheelchair and battling several illnesses, and would pose no danger to anyone if released.
But prosecutors said Madoff has improved since he resumed kidney dialysis treatment in November, and while ill he could live more than 18 months.
They also said his request last year that President Trump commute his sentence was mainly so he could care for his wife Ruth in her old age, "apparently confident" his health would allow it. Trump has not acted on that request.