In 1974, Mathias graduated from the University of Maryland, Baltimore County, with a Bachelor of Arts degree in Political Science.

[citation needed] Mathias and his father established a business in downtown Ocean City and built an amusement and arcade operation.

In 2006, Mathias was elected to the Maryland House of Delegates for District 38B, along with fellow Democrat Norman Conway of Salisbury, where he would serve for one term before running to replace retiring State Senator J. Lowell Stoltzfus.

Mathias won re-election in 2014 over Republican state delegate and former mayor of Pocomoke City Mike McDermott.

In the 2018 general election, Mathias lost his re-election bid to Republican state delegate and former Ehrlich administration official Mary Beth Carozza, also of Ocean City.