A federal jury found a former water polo coach at the University of Southern California guilty on Friday of taking thousands of dollars in bribes in exchange for designating high school applicants as recruits so that they would be favored in the college admissions process.

The defendant, Jovan Vavic, has been the only coach to stand trial rather than take a guilty plea in the federal investigation known as Operation Varsity Blues, in which wealthy parents paid bribes to have their children admitted to elite schools.

Mr. Vavic was a star at U.S.C. who had stewarded the men’s and women’s water polo teams to 16 national championships. His lawyers argued during the trial that he had been pressured by the fund-raising culture of the university to recruit athletes whose families could afford to make large donations, but that he wanted them to be real athletes.

After a half-day of deliberations, the jury in Boston rejected those arguments, siding with prosecutors who said that Mr. Vavic received more than $200,000 in bribes from William Singer, known as Rick, a college admissions consultant to the rich, in exchange for facilitating the recruitment of athletes with trumped up credentials.

Mr. Vavic was found guilty on all counts, including conspiracy to commit mail and wire fraud and conspiracy to commit federal programs bribery.

Mr. Singer, who is cooperating with the government, has described himself as a “concierge” consultant for wealthy families, boasting that he could get their children into the universities with the best brand names in the country.

During the trial, Mr. Vavic’s lawyers said that he never misappropriated any money or committed any fraud. They said that about $100,000 of the cash was deposited into a U.S.C. account for the water polo team. Another $120,000 went to pay private school tuition for his sons, money that they said came in the form of scholarships from Mr. Singer’s foundation. Prosecutors said the foundation was a conduit for bribery.

The sweeping federal investigation exposed the dirty underbelly of college admissions. Federal prosecutors said that a canny college consultant — Mr. Singer — was able to manipulate the preference given to recruited athletes for students who would otherwise not qualify. Prosecutors were careful to say, however, that the universities involved were not on trial and that they were the unknowing victims of the fraud.

The jury in Mr. Vavic’s trial seemed to accept the prosecution’s argument that the case was not about donating a building or even a large amount of money to a university, but about lying and cheating on a college application.

In a separate part of the probe, investigators charged that parents were bribing Mr. Singer to doctor the standardized test scores of their children in some cases by exploiting the system that allows learning disabled students to go to special testing locations, where Mr. Singer could install his own agents.

U.S.C., which has worked to overcome its reputation as the “University of Spoiled Children,” was a focus of the investigation, and it fired Mr. Vavic after his arrest in March 2019.

But the investigation snared dozens of parents, coaches, exam administrators and others in a scheme that implicated college athletic programs at not only U.S.C. but Yale, Stanford, Wake Forest and Georgetown. Most athletic officials and parents implicated in the scheme have pleaded guilty rather than take their chances at trial.

Lori Loughlin and Felicity Huffman, the actresses, have already completed their prison sentences. John Wilson, a former executive at Staples and at Gap and the founder of a real estate and private equity firm, was sentenced to 15 months, the longest sentence so far. Mr. Vavic helped recruit Mr. Wilson’s son to the water polo team.

Susan C. Beachy contributed research.