McKennie picked up the injury during the first leg of Juventus' UEFA Champions League round of 16 first leg against Villarreal on February 22 which ended 1-1.
It was initially anticipated that the United States of America international would be out for eight weeks but he will not be making a return until the start of the 2022/2023 season.
Juventus manager Maximiliano Allegri made the revelation after the Old Lady defeated Spezia 1-0 in Serie A on Sunday.
"The season is over for Weston because of his injury. He'll be back next season," Allegri told DAZN.
The 23-year-old has made 28 appearances across all competitions for Juventus this season, scoring four goals.
Juventus' victory over Spezia came courtesy Alvaro Morata's 21st minute strike and Allegri was delighted with the performance of his boys.
"It's always important for the forwards. I'm happy with the goal and the performance," Allegri said at his post-match news conference when asked about Morata's goal.
"Today, after so many matches with the same players, all you have to do is congratulate the boys. It wasn't easy to win. We dropped in the second half.
"For the first time we are mathematically fourth in the rankings. In the first half we had to finish the game, in the second it was normal that we would suffer a little."
McKennie will also miss USA's final three FIFA World Cup qualifying games later in March.
