Johnstone-Burt had small roles in episodes of
Rake and
Sea Patrol and starred in the film
Before the Rain. He also appeared as "a young thug" in
Underbelly: The Golden Mile. A week before he graduated from NIDA, Johnstone-Burt was approached to play the brain damaged Fish Lamb in the
television adaptation of
Tim Winton's
Cloudstreet. After attending the audition, the actor believed he had done a good enough job to secure the role. He told a
The Daily Telegraph reporter, "I supposed I walked out thinking I did a good job – seeing how I worked with [director Matthew Saville] and taking his direction. Then I had to sit by my phone for a month and hopefully get a call." A reporter for the
Herald Sun also included Johnstone-Burt in their "11 Faces To Watch in 2011" list. The actor next appeared as Seb in
John Duigan's film
Careless Love. He also travelled to Hollywood for the pilot season, where he auditioned for upcoming television shows and films. ''Miss Fisher's Murder Mysteries'' was renewed for a second series in which he reprised his role. In March 2012, Johnstone-Burt joined the cast of drama series
Tricky Business. The following month, Johnstone-Burt revealed that he had filmed a guest role for the soap opera
Home and Away. The actor called his character,
Jamie Sharpe, "a super-creepy stalker guy" and said he had worked a lot with
Ada Nicodemou (
Leah Patterson-Baker). He also appeared alongside
Magda Szubanski in the musical drama film
Goddess. Johnstone-Burt appeared in the Network Ten drama
The Wrong Girl as Vincent, the brother of lead character Lily played by
Jessica Marais. He reprised his role of Hugh Collins in the 2020 feature film
Miss Fisher and the Crypt of Tears. It was shot on-location in Melbourne and Morocco in 2018. The following year, he appeared in
Rick Donald's comedy series ''
Australia's Sexiest Tradie. In 2023, Johnstone-Burt played Henry Broad in the British drama series Ten Pound Poms. He also appeared in the British sitcom Queen of Oz''. In 2024, Johnstone-Burt appeared in the
7plus series
Roast Night. He also guest-starred in an episode of the crime comedy drama series
Return to Paradise. ==Personal life==