The Canadian singer told his screaming fans: “Everybody give it up for this kid...I just wanted to say, he is very inspirational, he shows other people to stand up for what they believe in.”
Casey then introduced Bieber’s song Never Say Never.
Bieber also spent time with Heynes backstage asking him about his experience of striking back at school bullies who were tormenting him.
Heynes, 15, made headlines after standing up to a bully at his Western Sydney school. After sustaining punch after punch from one particular tormenter he finally lost his rag, body slamming him to the ground.
The video of the incident went viral on the internet.
Bieber flew the Sydney teen and his family out specially from Sydney for VIP treatment at the Rod Laver Arena in Melbourne.
Bieber knows a little bit about bullying - he had eggs thrown at him during his London show. He has also been very supporting of anti-bullying campaigns in the past.
The teenage pop superstar is currently touring Australia.
Watch Justin Bieber meeting Casey Heynes.