The team announced on Monday the results of an MRI exam that revealed the tear Beason sustained in a 28-21 loss at Arizona in the season opener Sunday. He was carted off the field in the second half.
Beason signed a $51 million, six-year deal this summer, including a $20 million signing bonus. A first-round pick in 2007, he has played inside and outside linebacker for the Panthers and is one of their defensive leaders.
He had started 65 straight games for the Panthers.
The injury occurred while Beason was covering former Panthers tight end Jeff King, who scored on a 48-yard touchdown after Beason fell down without contact.
Dan Connor, a former third-round draft pick out of Penn State who started half of the season last year, will take over for Beason at middle linebacker.
"You can pretty much imagine what it's going to be like to lose a leader like Jon," said Carolina outside linebacker Thomas Davis, who has missed much of the previous two seasons with a torn knee ligament. "He's a guy who comes in day-in and day-out and gives you everything he has. It's going to be extremely tough for us.
"But we have some guys who have to step up now. You know, Dan Connor is a guy who has stepped up and played well for us in the past."
It's the same leg that has given Beason problems the last several months.
It was originally diagnosed as Achilles tendinitis, but Beason said that wasn't the case and that an MRI revealed he had inflammation in the bone.
He had three screws inserted in his foot and was told he would need to be out three to four weeks to recover. Beason came back in less than three weeks to play in Sunday's game against Arizona.
Wide receiver Steve Smith said Beason's decision is a reflection of the team's attitude.
"I'm just happy and honored to be on this team because we had guys out there that were blowing out tires to fight," Smith said. "It doesn't get any better than that. You don't get guys in the locker room like that. It rarely comes and when you have a guy who does that you surely miss him."