After her graduation, Mordaunt's employment was focused on public relations in various sectors. Under Prime Minister John Major she was Head of Youth for the Conservative Party, before working for two years as Head of Broadcasting for the party under party leader William Hague. She then worked as a communications specialist for the Freight Transport Association before, in 2000, working briefly as Head of Foreign Press for George W. Bush's presidential campaign. She was director of communications for the Royal Borough of Kensington and Chelsea from 2001 to 2003, before leaving to set up a new Anglo-American website called 'virtualconservatives'. She worked for the Bush campaign again in 2004. She was a director at the Community Fund – which merged administratively with the New Opportunities Fund to create the Big Lottery Fund – and, in 2006, became one of six Directors at charity Diabetes UK.