In 2003, March made her film debut with a supporting role in the political comedy "Head of State" opposite Chris Rock. She later appeared in the films "Mr. & Mrs. Smith", "The Treatment", and "Falling for Grace", the latter two romantic comedies. March also appeared in the 2009 film "The Invention of Lying" as the woman Ricky Gervais's character tells the world will end unless she has sex with him. She later co-starred in the independent films "Why Stop Now?" and "Innocence".