Isla Lang Fisher was born on February 3, 1976 in Muscat, Oman, to Scottish parents Elspeth Reid and Brian Fisher, who worked as a banker for the U.N. She spent her early childhood in Bathgate, Scotland, before moving to Perth, Australia with her family in the early 1980s. From a young age, Isla showed an interest in both acting and writing. At nine years old, she was appearing in Australian TV commercials. She landed some small parts in the Australian television series Bay City (1993). This led to a bigger part in the television series Paradise Beach (1993). When that show ended, she landed a role in the long-running Australian soap opera Home and Away (1988). While working on that show, she indulged in another of her passions, writing, and published two best-selling novels, "Seduced By Fame" and "Bewitched". In 1997, she was picked by the readers of FHM magazine as #35 on the list of the "100 Sexiest Women in the World", and in 2003, she placed 26th.

Isla has since appeared in the films Wedding Crashers (2005), The Lookout (2007), Hot Rod (2007) and Definitely, Maybe (2008), Confessions of a Shopaholic (2009), and Now You See Me (2013).