A Manhattan jury on Tuesday found former President Donald J. Trump liable for sexually abusing and defaming E. Jean Carroll and awarded her $5 million in damages. More than a dozen women have accused Mr. Trump of sexual misconduct over the years, but this is the only allegation to be affirmed by a jury.

In the civil case, the federal jury of six men and three women found that Ms. Carroll, 79, a former magazine writer, had sufficiently proved that Mr. Trump sexually abused her nearly 30 years ago in a dressing room of the Bergdorf Goodman department store in Manhattan. The jury did not, however, find he had raped her, as she had long claimed.

The jury, in returning the verdict shortly before 3 p.m., also found that Mr. Trump, who is running to regain the presidency, defamed Ms. Carroll in October when he posted a statement on his Truth Social platform calling her case “a complete con job” and “a Hoax and a lie.” His lawyer said he intended to appeal.

Mr. Trump’s lawyers called no witnesses, and he never appeared at the trial to hear Ms. Carroll, who had sued him last year, deliver visceral testimony about the attack she said had ended her romantic life forever.

On Tuesday, Ms. Carroll nodded along as a court clerk read the verdict aloud, her nod growing more pronounced as the clerk said Mr. Trump was liable for defamation. She walked out of the courthouse grinning from ear to ear, holding hands with her lawyer, Roberta A. Kaplan. A woman yelled to Ms. Carroll, “You’re so brave and beautiful.” Ms. Carroll replied, “Thank you, thank you so much.”

In a later statement, she said: “I filed this lawsuit against Donald Trump to clear my name and to get my life back. 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.”

For decades, Mr. Trump had reveled in projecting the image of a man irresistible to women, engineering tabloid headlines like “Best Sex I’ve Ever Had,” appearing in the introduction of a 1999 Playboy magazine centerfold video and bragging in an exchange caught on video about how, as a celebrity, he could grab women’s genitals with impunity. Now the jury has labeled him not a Lothario but an abuser.

Its unanimous verdict came after just under three hours of deliberation. The findings are civil, not criminal, meaning Mr. Trump has not been convicted of any crime and faces no prison time.

In a Truth Social post after the verdict, Mr. Trump continued to insist that he did not know Ms. Carroll: “I have absolutely no idea who this woman is. This verdict is a disgrace — a continuation of the greatest witch hunt of all time!”

His lawyer Joseph Tacopina said outside the courthouse that the case would be appealed. He also defended Mr. Trump’s absence from the courtroom and his decision not to testify in his own defense.

“This was a circus atmosphere, and having him be here would be more of a circus,” Mr. Tacopina said.

He noted that Mr. Trump had denied Ms. Carroll’s allegation in a video deposition that her lawyers played for the jury. He also said Ms. Carroll’s lawyers should never have been allowed to play the “Access Hollywood” recording for the jury, in which Mr. Trump was captured boasting in vulgar terms about grabbing women by the genitals.

And he complained about the decision by the judge, Lewis A. Kaplan, to have an anonymous jury hear the case, with their names kept even from the lawyers.

“There were things that happened in this case that were beyond the pale,” said Mr. Tacopina, who also complained about what he said was “bias displayed by the court.”

Mr. Tacopina clashed with Judge Kaplan at times and even filed a motion seeking a mistrial based on “pervasive, unfair and prejudicial rulings” based in part on what he described as the judge’s improperly sustaining objections by Ms. Carroll’s lawyers, who argued that his questions were argumentative.

At one point, Judge Kaplan quoted the definition of “an argumentative question” from Black’s Law Dictionary, reading it aloud to Mr. Tacopina.

During his instructions to the jury on Tuesday, the judge explained their three options for finding Mr. Trump liable for battery, meaning an assault on Ms. Carroll: that he had raped her, sexually abused her or forcibly touched her. A unanimous vote would affirm that Ms. Carroll had proven that it was more likely than not to be true that he had committed an offense, the judge explained.

In a criminal case, when jurors are asked to assess guilt, they must meet the much higher standard of beyond a reasonable doubt.

It was not clear why jurors chose the lesser offense of abuse over rape. Sexual abuse is defined in New York as subjecting a person to sexual contact without consent. Rape is defined under state law as sexual intercourse without consent that involves any penetration of the penis in the vaginal opening.

During the trial, Ms. Carroll, a former advice columnist for Elle magazine who was well known in Manhattan media circles, had testified that the attack followed a chance encounter one evening at Bergdorf’s, a fashionable department store on Fifth Avenue. Mr. Trump, she said, asked her to help him buy a present for a female friend.

They ended up in the lingerie section, where he motioned her over to a dressing room, shut the door and began assaulting her. He shoved her against the wall and, using his weight to pin her, he pulled down her tights and forced his fingers into her vagina and then, she said, his penis.

She pushed back, stamped with her heels and used her knee to push Mr. Trump off her, and she fled the store. Other than telling two friends, she kept the encounter a secret for more than 20 years until she disclosed it in a 2019 book excerpt in New York magazine.

Ms. Carroll and 10 other witnesses called on her behalf testified during the two-week trial. They included the friends — Lisa Birnbach, a journalist and author, and Carol Martin, a former TV anchor — in whom she had confided almost immediately after the attack, telling them what Mr. Trump had done. Two other women testified that Mr. Trump had sexually assaulted them years ago in ways that were similar to the way Ms. Carroll described being attacked.

Ms. Carroll was able to bring her lawsuit after New York State last year enacted a new law granting adult sexual abuse victims a one-year window to sue people they say abused them, even if the criminal statute of limitations had long expired.

“For far too long, survivors of sexual assault faced a wall of doubt and intimidation,” her lawyer, Ms. Kaplan, said after the verdict. “We hope and believe today’s verdict will be an important step in tearing that wall down.”

While Mr. Trump avoided the trial, he repeatedly attacked Ms. Carroll from outside the courtroom during the proceeding, initially on Truth Social and last week in an interview from a golf course in Ireland, where he suggested he would return to New York to testify in his own defense. In the end, he did not.

In his closing argument, Mr. Tacopina argued that there was no need for Mr. Trump to appear, because the incident at Bergdorf’s did not happen. He said that he presented his client’s defense through his cross-examination of Ms. Carroll and her witnesses.

“If something is completely made up,” Mr. Tacopina told the jury, “the only way to defend yourself against that accusation is by challenging the people who made it up and the story itself.”

During this cross-examination, one area he focused on was Ms. Carroll’s testimony that she did not scream during the assault.

“I’m not a screamer,” she responded, adding that she was in too much of a panic. “I was fighting,” she said. “You can’t beat up on me for not screaming.”

Mr. Tacopina replied: “I’m not beating up on you. I’m asking you questions, Ms. Carroll.”

“No,” Ms. Carroll interjected. She said that one of the reasons women do not come forward “is because they are always asked why didn’t you scream. Some women scream. Some women don’t. It keeps women silent.”

Ms. Carroll, her voice rising as she testified, said, “I’m telling you, he raped me, whether I screamed or not.”

The verdict comes as Mr. Trump confronts a barrage of legal actions. In April, he pleaded not guilty to New York fraud charges stemming from hush money paid to a porn star, and he faces a civil fraud lawsuit brought by New York’s attorney general.

Mr. Trump is also under investigation in Georgia over attempted interference in the 2020 election, and a federal special counsel is examining the discovery of sensitive documents at Mar-a-Lago, as well as his role in the events leading up to the Jan. 6, 2021, assault on the Capitol. Mr. Trump has denied wrongdoing in all the cases, and argued that the lawsuits and investigations are meant to drag him down.

Ms. Carroll, during her testimony, was asked by another of her lawyers, Michael J. Ferrara, whether she was glad she had spoken publicly about what Mr. Trump did to her or regretted doing so.

“I have regretted this about a hundred times, but in the end — in the end, being able to get my day in court finally is everything to me,” she said. “I’m glad that I got to tell my story in court.”

Nate Schweber, Hurubie Meko and Maggie Haberman contributed reporting.