Sivan portrayed the younger Wolverine in X-Men Origins: Wolverine (2009) and starred as the titular character in the Spud film trilogy. In 2017, he became the youngest recipient to receive a GLAAD Stephen F. Kolzak Award. In 2018, he received a Golden Globe nomination for Best Original Song for "Revelation", from the film Boy Erased, in which he also had a supporting acting role. He has since starred in the film Three Months (2022) and the series The Idol (2023).