Turner was released after the Chargers first attempted to trade him.
Turner had no guaranteed money left on a four-year, $45 million extension he signed with the Panthers in 2017. The Chargers save $11.5 million in salary cap space with the move.
Turner, 27, was limited to just nine games last season because of a groin injury.
While with the Panthers, he was selected to five Pro Bowls in his first six NFL seasons. Selected in the third round of the 2014 draft by Carolina, he has played in 93 career games with 89 starts.