Mathews, 28, is a former seventh-round pick of the Colts back in 2010. He spent four years in Indianapolis before signing on with the Chargers in 2014.
Mathews was testing the open market as an unrestricted free agent for the third consecutive year.
In 2015, Mathews appeared in all 16 games for the Chargers and recorded 23 tackles and a sack. Pro Football Focus has him rated as the No. 121 interior defensive lineman out of 123 qualifying players.