Mallahan began his political activism in Chicago while working as the President of Century Supply Company. There Mallahan helped establish United Power for Action and Justice and received training and work as a community organizer from the Industrial Areas Foundation. After returning to Seattle in 2000 Mallahan worked on fellow Industrial Areas Foundation alumnus Barack Obama's presidential campaign but it was not until the 2009 Seattle mayoral race that he ran for political office. In addition to his work earlier work with Representative Al Swift Mallhan later worked as a legislative aide to Washington Republican Senator Slade Gorton. Since his return to Seattle and registering to vote in April 2000 elections records in King County show that Mallahan had voted in 12 of the 25 elections he was eligible to participate in.