Trevor Bauer, the star pitcher for the Los Angeles Dodgers who remains under investigation for sexual assault, will not pitch in the majors again this season. Major League Baseball and the players’ union agreed Friday to extend his administrative leave until the end of the postseason, a league official said.

M.L.B. initially placed Bauer on paid leave on July 2, but the league’s collective bargaining agreement required consent from the players’ union to continue extending it, which has already occurred multiple times. With only 21 games remaining in the Dodgers’ regular season entering Friday’s game, however, and with Bauer still under investigation by M.L.B. and the authorities in Southern California, the sides agreed to sideline him for the rest of the 2021 campaign, including the playoffs.

Any league discipline for Bauer, if he is charged with a crime or found to have violated any league policies, would come after the World Series.

Bauer, 30, has been under investigation by the Pasadena Police Department since a 27-year-old woman accused him of assaulting her in Pasadena, Calif., in May. In late June, the woman sought a temporary restraining order against Bauer, which was granted.

On Aug. 19, a Los Angeles judge heard testimony and evidence from both sides and dissolved the temporary protection order against Bauer and rejected the woman’s request for a more permanent one. The judge called aspects of the woman’s protective order request “materially misleading” and, although the judge noted that photographs of the woman’s injuries were “terrible,” she ruled that Bauer had not exceeded limits on rough sex set by the woman.

In her filings and testimony, the woman said that she had initiated contact with Bauer and that what had begun as a consensual relationship in April, with some agreed-upon rough sex, led to sexual acts that were not consensual. She also said she had been choked with her hair until she lost consciousness. She said that she had returned to Bauer’s house in Pasadena in May and had established a safe word that would signal her desire to stop but that she was again choked until she lost consciousness and was punched.

Bauer has denied the woman’s accusations and has insisted his relationship with her was “brief and wholly consensual,” according to his agent Jon Fetterolf.

On Aug. 27, the Pasadena Police Department presented Bauer’s case to the Los Angeles County District Attorney’s Office. Bauer has not been charged or arrested. A Pasadena Police Department spokeswoman declined to comment on Friday. The L.A. District Attorney’s Office did not immediately respond for a request for comment.

While M.L.B. has often let the criminal process play out before delivering its own punishments, a conviction, charge or arrest is not required for a player to be suspended. Since M.L.B. and the players’ union enacted a policy in 2015 governing domestic violence, sexual assault and child abuse, 13 players have been suspended after investigations, many of them without charges, with bans ranging from 15 to 162 games.

M.L.B.’s investigation into Bauer also encompasses an incident that came to light last month in a Washington Post article that detailed how an Ohio woman had sought a protective order against him last year after accusing him of punching and choking her without consent during sex. According to the report, which relied on sealed court records and other documents, the woman dropped the request six weeks after filing it and after Bauer’s lawyers threatened legal action. Bauer called the report “a false narrative” and accused the woman of attempting extortion.

Bauer, who won the National League Cy Young Award in 2020, signed a free-agent deal with the Dodgers, the reigning World Series champion, for three years and a guaranteed $102 million during the past off-season. He has an 8-5 record and a 2.59 E.R.A. this season for the Dodgers but has not pitched since June 28.