SANTA MONICA, Calif. — A California jury in a civil case ruled on Tuesday that Bill Cosby sexually assaulted a woman at the Playboy Mansion in 1975 when she was a teenager and ordered the comedian to pay her $500,000 in damages for emotional distress from the incident.

Judy Huth had testified that the comedian invited her and a friend to the mansion when she was 16, and he was 37, and forced her to perform a sex act.

The verdict came nearly a year after Mr. Cosby was freed from prison when Pennsylvania’s highest court threw out his sexual assault conviction in a different criminal case there.

Ms. Huth’s lawsuit was the first civil case against Mr. Cosby to come to trial.

Ms. Huth, now 64, said she was “elated” by the ruling in the case, which she filed in 2014 after media reports detailed accusations against Mr. Cosby by multiple women. Those reports helped stir up memories of her encounter with Mr. Cosby, Ms. Huth said, and triggered four years of anxiety and other symptoms.

“It’s been so many years, so many tears,” Ms. Huth told reporters outside California Superior Court in Santa Monica. “It’s been a long time coming.”

Ms. Huth told the jury that Mr. Cosby had invited her and the friend to the mansion a few days after they met the then-famous actor and comedian at a public park. After she emerged from a bathroom, Mr. Cosby took her hand and used it to masturbate his penis, she said.

Mr. Cosby, who did not appear in person at the trial, denied Ms. Huth’s allegation. His defense team will appeal the verdict, Cosby spokesman Andrew Wyatt said.

“Mr. Cosby continues to maintain his innocence and will vigorously fight these false accusations, so that he can get back to bringing the pursuit of happiness, joy and laughter to the world,” Wyatt said in a statement.

Mr. Cosby, 84, is best known for his role as the lovable husband and father in the 1980s television comedy series The Cosby Show, earning him the nickname “America’s Dad.” But his family-friendly reputation was shattered after more than 50 women accused him of sexual assaults over nearly five decades.

Ms. Huth brought the case under a California law that allows people who claim they were abused as children to file civil cases years later as adults.

Three other women who have accused Mr. Cosby of abuse attended the trial and told reporters they felt vindicated by the verdict. Lili Bernard, who has a civil lawsuit pending against Mr. Cosby in New Jersey, said the ruling was “important for every sexual assault survivor who has not received justice.”

“We will never give up,” she said.

The jury did not rule entirely in Ms. Huth’s favor. By a 9-3 vote, they said she had not provided “clear and convincing evidence” that Mr. Cosby had acted with “malice, oppression or fraud.”

If jurors had voted yes on that question, they could have provided additional punitive damages to Ms. Huth.

In video of a deposition shown to jurors, Mr. Cosby said he did not remember Ms. Huth. But he said the incident could not have happened because he would not have pursued sexual contact at that time with someone who was under age 18.

Cosby attorney Jennifer Bonjean challenged Ms. Huth’s account throughout the trial, including her revised timeline.

When the lawsuit was filed in December 2014, Ms. Huth said the incident occurred in 1974, when she was 15. She told jurors she recently concluded that she had been mistaken about the year and now believes it happened in 1975. — Reuters