He began his acting career with a supporting role in the horror film Carrie (2013). He gained wider recognition for starring as a teenage cancer patient in the romantic drama film The Fault in Our Stars (2014) and for his supporting role in The Divergent Series (2014–2016).

In 2017, Elgort played the title character in Edgar Wright's action thriller Baby Driver, for which he received a Golden Globe Award nomination for Best Actor in a Motion Picture – Musical or Comedy. He starred as Tony in Steven Spielberg's musical film West Side Story (2021) and since 2022, has portrayed Jake Adelstein in the crime series Tokyo Vice.