Barkov injured himself on Thursday during his first ice training with his team's training camp ahead of the season.
He was operated on on Friday, according to Florida's coach Paul Maurice.
Barkov is expected to be out for several months and the entire season is at risk. This means that he also appears to miss the Olympic Games in Milano-Cortina in February where NHL players are back for the first time since Sochi 2014.
There, Finland plays in the same group as Sweden, Italy, and Slovakia.
The exact length of the convalescence is not clear until the operation is completed, according to Maurice.
The 30-year-old Barkov has led Florida Panthers to two consecutive Stanley Cup titles and accounted for 71 points (20 goals+51 assists) in the regular season and an additional 22 points (6+16) in the playoffs last season.
He has been awarded the Selke Trophy three times as the NHL's best defensive forward.
For Florida, it is also a hard blow as the team already lacks Matthew Tkachuk, who will be out until December after an operation during the summer.
