Donald Trump has promised to appeal and called it a "disgrace" after a jury found him liable for sexually abusing a writer in the 1990s.
The former US president was also found to have defamed E Jean Carroll, but the civil trial rejected her claim she was raped during the encounter.
Trump must pay the former Elle magazine advice columnist $5m (£4m) in damages.
Ms Carroll, 79, said they ran into each other in a department store in Manhattan in 1995 or 1996 and that Trump ended up raping her in a changing room.
She also said he defamed her by claiming she made up the story.
Trump lashed out on his Truth Social site, calling the outcome "a continuation of the greatest witch hunt of all time" and a "disgrace".
He claimed the judge was biased and made sure "the result was as negative as it could possibly be, speaking to, and in control of a jury from an anti-Trump area..."
The nine-person jury deliberated for just under three hours before finding him guilty on Tuesday.
Following the verdict, Ms Carroll said she sued Trump to "get my life back" and that "today the world finally knows the truth".
"This victory is not just for me but for every woman who has suffered because she was not believed," she said.
She testified that the attack happened after a chance encounter with Trump at the Bergdorf Goodman store across the street from Trump Tower.
She said it started as a light-hearted interaction in which they teased each other about trying a piece of lingerie, before Trump became violent inside a dressing room.
Trump - who did not attend the trial and waived his right to testify or present a defence - has insisted he never sexually assaulted Ms Carroll or ever knew her.
The 76-year-old, who is hoping to retake the White House in 2024, will not have to pay the compensation as long as the case is on appeal.
Ms Carroll told jurors that Trump had "shattered" her reputation.
Her defamation claim was based on an October 2022 post on Truth Social in which he called her allegations a "complete con job" and "a hoax and a lie".
'No one is above the law'
As it was a civil case, Trump faces no criminal consequences - but his former aide Sean Spicer said the rape allegation would still be damaging.
"It's never a good thing to have a verdict against you... especially of this nature," he said.
Mr Spicer said: "Optics do matter in politics, but I think if you were president Trump right now... the charge of rape would have stung a lot."
Ms Carroll's lawyer, Roberta Kaplan, said the verdict was also a victory "for democracy itself and for all survivors everywhere".
"No one is above the law, not even a former president of the United States," she added.
During the seven-day trial, jurors were also shown a deposition by Trump confusing Ms Carroll for his ex-wife Marla Maples in a photograph - which her lawyers said undermined his argument that she was not his type.
Trump's lawyers previously said Ms Carroll had "abused the system" for "money, status and political reasons".
Speaking outside the court, Trump's lawyer Joe Tacopina said it was an "inconsistent verdict" but he was happy Trump "was not branded a rapist".
"For me it's about the results," he said.
"While it was strange, part of me was obviously very happy that Donald Trump was not branded a rapist. I didn't think there should be any liability findings so we'll pursue that."