The 17-year-old singer, who is currently touring around Australia, asked the audience to applaud Heynes after footage of him defending himself against a playground bully made him an internet sensation.
According to the Herald Sun, Bieber said: "'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." He then performed his hit song 'Never Say Never'.
The teen star tweeted a link to a news story on Heynes and referred to him as a "real life hero" and revealed that he tracked down the boy's family and flew them to the show as a "thank you". He also called him a "kid with a lot of courage" and said that he had made the show a "pretty special night".
Bieber was egged during his Sydney concert last Friday but carried on his performance, reportedly only stepping back momentarily to allow a stagehand to clean up the mess.
At his previous show, he was joined on stage by singer Chris Brown.
Watch an interview with Casey Heynes below: