Mr. Ernst, 55 years old, pleaded guilty in 2021 to bribery conspiracy, bribery and filing a false tax return, admitting to taking around $3.4 million in bribes in exchange for tagging at least 22 Georgetown applicants as tennis recruits, whether or not they actually played the sport. Getting such a designation nearly guarantees admission for the prospective students.

Mr. Ernst admitted to taking bribes through William “Rick” Singer, the mastermind of the admissions scheme who has confessed to racketeering, fraud and money laundering conspiracy, as well as obstruction of justice. Mr. Ernst also admitted to receiving direct payments from other parents under separate arrangements. One of those parents, Amin Khoury, was acquitted by a Boston federal jurylast month of bribery and bribery and fraud conspiracy charges.

Prosecutors said Mr. Ernst accepted more than $3.4 million in bribe payments over the course of a decade, beginning around 2008, and that in some years he used up to five of his six allotted recruitment slots for students whose families had paid bribes.

“Ernst’s criminal conduct was lengthy, pervasive, and highly profitable,” they said in a court filing ahead of the sentencing, adding that the coach had lied to Georgetown when it started investigating, didn’t pay taxes on all his earnings and offered to help Mr. Singer recruit additional coaches to the scheme.

Georgetown has said it uncovered irregularities in Mr. Ernst’s recruiting practices and placed him on leave in December 2017; he left the school the following June. Georgetown said it set new policies around student-athlete admissions in late 2018, including barring coaches from fundraising during recruiting, and imposing audits to see if recruited students actually joined the teams.

In a court filing ahead of the sentencing, Mr. Ernst’s legal team likened the coach to Icarus, flying too close to the sun with ultimately dire consequences. They said he was surrounded by wealth at Georgetown, but earned a relatively paltry salary himself and wanted to provide his own family with the same opportunities and luxuries his students had. When the chance to earn additional income arose, he took it.

“He got carried away, got in deeper every year and, like Icarus, was destined to come crashing down,” they wrote.

Mr. Ernst said in a February letter to U.S. District Judge Indira Talwani that he “became sick inside with self-hatred,” but “justified my actions with a list of grievances and a host of lies.”

In addition to the prison term, Judge Talwani sentenced Mr. Ernst to two years of supervised release—the first six months of which he must spend in home confinement—and said he must forfeit $3.4 million he earned from the scheme.

Prosecutors had asked the judge to sentence Mr. Ernst to four years in prison, while his legal team asked for a prison sentence of one year and one day.

Write to Melissa Korn at melissa.korn@wsj.com