Cox, 26, spent his first four seasons with the Jacksonville Jaguars and put up strong numbers when healthy. Last season he totaled 60 tackles, four interceptions and 11 passes defended. His health is a concern as he missed four games last year with a back injury and he's missed a total of 17 games over the past three seasons.
The deal includes a $5.2 million signing bonus and $10.25 million in guaranteed money. San Diego had targeted several cornerbacks in free agency, but decided to sign Cox on Wednesday before he went on to a scheduled visit with the Saints.
Former San Diego cornerbacks Quentin Jammer and Antoine Cason both became free agents this offseason, creating an area of need for the Chargers. Cox should go a long way to helping San Diego replace its former starters and patch up the defense.