The right-handed pitcher -- a current free agent who was one of the best in the game from 2012 through 2015 -- made the revelation during an explosive testimony during a trial related to the 2019 death of former MLB pitcher Tyler Skaggs.

On the stand, Harvey -- who was teammates with Skaggs on the Angels at the time of the pitcher's death -- told the courtroom that he used to party with cocaine.

When asked about his use of the drug and if he lied about taking it when he was with the Mets ... he said, according to ESPN reporter T.J. Quinn, "No one really asked."

Per Quinn, Harvey told the courtroom he was still using the drug after he signed with the Angels following the 2018 season.

Harvey -- who played for the Mets, Reds, Angels, Royals and, most recently, the Orioles, later said, "no one from teams ever asked if he was still using drugs," Quinn reported.

The news is a bombshell, but it was hardly the only one Harvey dropped during the testimony.

The 32-year-old, who testified under immunity, said he and Skaggs had talked about drug use when they were teammates, and added that the two had taken the substances in clubhouses.

Harvey said he'd take painkillers, and said that, according to Quinn, Skaggs told him "he crushed and snorted oxy on the toilet paper dispenser in the clubhouse bathroom."

Harvey also said, per Quinn, that he did give Skaggs Percocets. He also said he obtained pills from ex-Angels staffer Eric Kay, who's been accused of supplying Skaggs with the drugs that investigators say might have led to his death.