The Warriors said in a press release that Thompson had surgery performed by Dr. Richard Ferkel in Los Angeles Wednesday morning.
With an estimated nine-month recovery process, the five-time All-Star will miss the entire 2020-2021 season.
The injury happened the day before the 2020 NBA Draft on Thursday, Nov. 18, while Thompson was working out in Los Angeles.
Thompson had recently recovered from an ACL tear in his left knee, which he sustained during the 2019 NBA Finals against the Toronto Raptors.
Doctors and Warriors' General Manager Bob Myers have both said they expect to see "great things" from the beloved "Splash Brother" when he eventually returns for the 2021-2022 season.