She denied online speculation that the disgraced financier and sex offender had introduced her to Donald Trump, saying she had met the future president at a New York City party in 1998, two years before crossing paths with Epstein at another event.
She also urged Congress to hold public hearings for Epstein victims to tell their stories under oath, raising the prospect of further public attention on an issue the president wants to go away.
"The lies linking me with the disgraceful Jeffrey Epstein need to end today," Melania Trump said, reading a statement and declining to take questions from reporters.
"I am not Epstein's victim," she said, responding to what she said were false smears against her.
Her extraordinary address, delivered in the White House foyer, renews scrutiny of the Epstein case that has roiled Donald Trump's presidency as even some supporters say his administration mishandled disclosures from government files.
Last week, the president fired Attorney-General Pam Bondi, who had drawn the ire of Trump loyalists over the Justice Department's slow release of millions of Epstein-related files.
Trump, a onetime friend of Epstein, who said he cut ties with the financier in the early 2000s, is among many famous people - celebrities, politicians and intellectuals - named in the government files.
Melania Trump did not say why she chose to speak out on Thursday, resurrecting an issue that had largely slipped from the headlines amid the US-Israeli war against Iran.
But Marc Beckman, her senior adviser, said "First Lady Melania Trump spoke out now because enough is enough. The lies must stop."
"A first lady in contemporary times has not publicly addressed controversy in this way, and certainly never from the state floor of the White House, so this took guts," said Michael LaRosa, former press secretary to first lady Jill Biden.
Epstein, who pleaded guilty in 2008 to two Florida felonies, including procurement of a minor for prostitution, was facing federal charges of sex-trafficking minors in 2019, when he died in jail in what was ruled a suicide.
"I have never been friends with Epstein," Melania Trump said. "Donald and I were invited to the same parties as Epstein from time to time, since overlapping in social circles is common in New York City and Palm Beach."
The president has sought for months to move past discussions about Epstein.
His administration, under pressure from the president's political base, ordered the US Justice Department to release files tied to criminal probes of Epstein in compliance with a transparency law passed by Congress.
The files include a 2002 email from Melania Trump to Epstein's convicted associate Ghislaine Maxwell, about a New York magazine piece.
"Nice story about JE in NY mag. You look great on the picture," the email reads. "Give me a call when you are back in NY."
On Thursday, Melania Trump described her email to Maxwell as just "casual correspondence," and "a trivial note."
Around a dozen Epstein survivors opposed the first lady's proposal for public hearings, saying in a statement they had already done enough to publicise his crimes through testimony and reports and that it was up to the US Justice Department to follow through. They also called on the Trump administration to comply with the Epstein Files Transparency Act.
with AP