Beason, who signed a five-year contract extension in July worth a reported $50 million, left in the third quarter of Sunday's 28-21 loss to Arizona and was carted off the field.
An MRI taken Monday revealed the Achilles tear.
Head coach Ron Rivera said that his understanding was the injury was on the upper part of the Achilles away from the foot.
Beason, 26, made the Pro Bowl each of the past three years and started all 65 games he played for the Panthers in four-plus seasons before going down with the injury.
He has collected 421 tackles, four sacks and eight interceptions since Carolina picked him No. 25 overall in the 2007 draft.
Beason was among a list of former Miami Hurricanes players named in reports about the recent booster scandal at that school.