Just after the massive chimney was brought down by more than 1,000 explosive charges, the streaker removed his pants and walked behind Nine Network's live national broadcast of the event, News.com.au reported.
The man kept his genitals covered with his hand.
Viewers took to Twitter to express their surprise.
"Watched the stack come down on tv, some naked fool behind the reporter. Stay classy port Kembla. #idiots," said Twitter user "Megara..."
"Don't look now @DaltsWorld but the Port Kembla #stackdemo has caused some locals to crack...," tweeted Melinda Farrell, referencing a moment when the streaker's buttocks were seen on screen.