[1] Gilbertson began acting at the age of six when he played the character of Sorrow in a local production of Madama Butterfly.

He made his screen debut in 2002, playing the role of the protagonists younger brother Greggy in Australian Rules.

[3][4] In 2010, Gilbertson won that year's AFI Young Actor Award for his performance as the underage WW1 soldier Frank Tiffin in Beneath Hill 60.

He made his US acting debut that same year, starring in the lead role of Emmett in Virginia, directed by screenwriter Dustin Lance Black.

Gilbertson is also known for his work in The Turning (2013), Fallen (2016), Hounds Of Love (2016), Upgrade (2018), Picnic at Hanging Rock (2018), In The Tall Grass (2019), The Peripheral (2022), and the Christopher Nolan–directed film Oppenheimer (2023).