The song plays with the idea of hidden identity and in the video Lowe appears as a haunting figure, under a veil concealing herself. The singer explained the meaning behind the track to Dazed.
"'Who's That Girl?' is about not recognising someone any more. It's always in the times of struggle - when something bad happens - that the biggest lessons are learnt and you realise who your true friends are. Some people step up and some people step down.” “'Who's That Girl?' is about a friend that stepped down when I needed her most. It was a blessing in disguise as it opened my eyes to all the things I couldn't see from such close proximity.”
As a stand alone track "Whose That Girl?" is a elegant number, but when combined with accompanying visual the song elevates to a higher level. Take a look up top.