Hanley trained as an opera singer at the Juilliard School. A teenage protégé of Leonard Bernstein, she was a soloist in the Great Composers Series singing his work Glitter and Be Gay (Candide). Much of her early work was in musical theatre prior to transitioning into TV and Film. She played Polly Peachum in a London production The Beggar's Opera which was part of London's West End summer (limited run) season Open Air Theatre productions at Holland, Cannazaro and Regent's Parks in the 1990s

Aside from her TV, film and voice over work, she was most known in Germany and in parts of Europe in the mid-late 90s as the Bacardi girl as well as for a comic worldwide commercial (NCR) opposite Toby Jones. In 2007 she released a European Dance single "Dance of the Euro Diva”. The music was composed by Éric Serra. The piece was originally written for the film The Fifth Element. Paramours included actor Javier Bardem, whom she met while working on Mouth to Mouth (aka Boca a Boca). Others included British TV personality James Hewitt, the former British household cavalry officer, who is most notable for being the long time lover of Diana, Princess of Wales. In the early 90’s she dated Phantom of the Opera collaborator Charles Hart (lyricist). Hart penned one of the songs on Hanley’s album A SIREN’S ODYSSEY. Rumored relationships include Hugh Grant, and Prince Albert of Monaco with whom European tabloids photographed her in the mid 1990’s sharing an intimate kiss while at a Paris nightclub, though no confirmation of a relationship was ever reported. She has been married to architect and entrepreneur Paul Millman since 2003.

Trivia: She was originally cast in a small role in Eyes Wide Shut -where she was filming for one month. With Kubrick's constant daily rewrites, eventually Hanley's scene was eventually dropped. She is a Vegan and active in animal activism.