"Who's That Girl" is an up-tempo electro R&B song performed by Australian singer-songwriter Guy Sebastian which features American rapper Eve. It was written by Sebastian, with Eve writing and performing the rap. Sebastian co-produced the song with Andre Harris. Released as a digital download on 5 November 2010, it was the only single released in Australia from Sebastian's retrospective album Twenty Ten. "Who's That Girl" reached number one on the ARIA Singles Chart, Sebastian's fifth of six number one singles in Australia and Eve's first. It was also Sebastian's seventh of 12 top ten singles on the Australian charts. It reached 5× platinum certification in 2014.
"Who's That Girl" was shortlisted for the 2011 APRA Song of the Year and won the APRA Urban Work of the Year. Sebastian received ARIA Award nominations for Single of the Year and Best Pop Release and won the Highest Selling Single ARIA. He was also nominated as "Most Popular Australian Artist". "Who's That Girl" also reached number one and platinum certification in New Zealand, Sebastian's second number one single there.