Mawle graduated from Bristol Old Vic Theatre School in 2002 in the same year he appeared in the Irish Hurling TV adverts for Guinness. He left in 2002 with no agent and worked as an assistant in a special needs school. He landed his first major role in a 2003 production of Troilus and Cressida playing Troilus for Shakespeare at the Tobacco factory, work at the Nuffield Theatre, Southampton, in Hamlet and in 2005 the Royal Exchange, Manchester's production of Antony and Cleopatra followed.