In their release, the Clippers said there was no timetable for his return.
Leonard was injured during the fourth quarter of Game 4 of the Western Conference semifinals against the Utah Jazz on June 14. He missed Los Angeles' final eight playoff games with what the team called a sprained right knee.
The Clippers rallied from a 2-0 series deficit to beat the Jazz in six games, before being eliminated in six games by the Phoenix Suns in the Western Conference finals.
The Clippers enter the offseason with Leonard's health and future at the forefront. Their franchise player has a player option in his contract and can choose to opt in for $36 million in 2021-22. If Leonard does so, he can then sign a four-year, $181.5 million extension that would start in 2022-23, according to ESPN's Bobby Marks.
"Obviously, if I'm healthy, the best decision is to decline the player option," Leonard said in December when asked about his future. "But that doesn't mean I'm leaving or staying. I'm focused on the season, like I said. We'll talk about that when the time is right."
Leonard doesn't have full Bird rights, and that would restrict him to a four-year, $176.2 million deal if he declines the option, according to Marks.
Leonard averaged 24.8 points, 6.5 rebounds and 5.2 assists in 52 regular-season games during his second campaign with the Clippers. He missed nine out of 10 regular-season games in April because of a foot injury.
Prior to Leonard's knee injury, the Clippers got a glimpse of their potential with Leonard and Paul George playing their best basketball together on the playoff stage. Leonard averaged 30.4 points, 7.7 rebounds and 4.4 assists while shooting 57.3% in 11 postseason games.
George picked up the load after Leonard went down, helping the Clippers reach the Western Conference finals for the first time in franchise history. George said "we'd be going on" to the NBA Finals had Leonard not been injured.
George, who signed a maximum contract extension prior to the 2020-21 season that guarantees as much as $226 million over five years, has repeatedly said he hopes Leonard stays in L.A. long term.
"Well, one of the commitments I made signing my contract was to show I'm here for the long run and I'm committed to this team," George said after the Clippers were eliminated by the Suns. "Hopefully, that weighs on [the Clippers players who have contract decisions to make]."
George would like to see how far the Clippers can go in the playoffs with a healthy Leonard.
"We've made great connections," George said of he and Leonard. "I think we've both grown, myself and Kawhi together. I think we really enjoy being teammates, and we see what we can be and what we can do. So, I'm happy. I'm happy to be his teammate."
The Clippers' training camp is scheduled to begin in late September.