Mathis, entering his 12th NFL season, started 13 games for the Lions in 2013 and had 47 tackles. Overall, he saw action in 15 games.
He was picked up midway through training camp and initially was a depth player used for mentoring some of Detroit's younger cornerbacks, however Mathis took over the starting job from Darius Slay in Week 3 and turned into the Lions' top cornerback in 2013.
Mathis played the previous 10 seasons for the Jacksonville Jaguars, amassing 30 interceptions.
ESPN NFL Insider Adam Schefter and ESPN.com Lions reporter Michael Rothstein contributed to this report.