Billed simply as Hannah, she placed "Our Kind of Love" in the UK Singles Chart in October 2000, where it peaked at No. 41.
She later sang the role of Starbird on the Soundtrack recording of Space Family Robinson, written by Julian and Stephen Butler and released by Pop! Records in May 2002 to coincide with the stage production (also featuring Hannah as Starbird) which ran for three weeks at London's Pleasance Theatre in May 2002.
In mid-2010, Waddingham played the Witch in the critically acclaimed production of Into the Woods at London's Open Air Theatre.
She originated the role of The Wicked Witch of the West in the West End production of The Wizard of Oz, which opened on 1 March 2011 at the London Palladium. She left the production on 4 September 2011. Waddingham won the whatsonstage.com Theatergoers Choice Award for Best Supporting Actress in a Musical for her performance.
In 2012, Waddingham starred in Chichester Festival Theatre's 2012 revival of Kiss Me, Kate. The show transferred to the Old Vic Theatre on London's South Bank in November 2012.