 After graduating from UC San Diego, Irwin worked as an engineer for three years at the Johns Hopkins University Applied Physics Lab, then for five years at Teledyne.In 2003, Irwin was appointed to the Thousand Oaks Planning Commission, ran for City Council the following year, and became mayor of Thousand Oaks in 2008.In 2014, Irwin successfully ran as a Democrat in the race to represent California's 44th State Assembly district, defeating Republican opponent Rob McCoy.