Skye Deva St. John Bennett was born on 2 May 1995 in London, England, to American parents. She holds dual British-American citizenship.

Skye began her professional career at the age of ten, when she got her first film role, playing Steven Seagal's daughter in the film Shadow Man. This led to further roles in film and television, including the role of Mina in the adaptation of David Almond's book Skellig, which won the Carnegie Medal and the Whitbread Children's Book Award, and the role of the mysterious girl who reads Tarot cards in the second season of Torchwood. She also appeared as young Martha in the television adaptation of Ken Follett's historical novel The Pillars of the Earth.

Skye's theatre debut at the age of 13 was in the role of Nadya in Peter Flannery's translation of Burnt by the Sun at the National Theatre in London in March 2009. She was also cast in a role in Mark Haddon's play Polar Bears at the Donmar Warehouse in London in spring 2010.

Skye's voice acting debut was in the 2017 Japanese fantasy role-playing video game Xenoblade Chronicles 2 and its 2018 prequel expansion Torna ~ The Golden Country. In both games she voiced the supporting heroines Pyra and Mythra.