Williams had arthroscopic surgery Tuesday to remove spurs from the front and back of his left ankle. Also, a loose bone fragment was removed from his right ankle.
Williams is expected to be on crutches for four to six weeks before rehabilitation, the Nets said in a statement. He will start light court activities in August and begin full basketball activities in September.
The former All-Star has been plagued by ankle trouble for the past two seasons and missed 18 games in 2013-14, including 16 because of a sprained left ankle. He averaged 14.3 points and 6.1 assists.