The younger boy allegedly produced a knife and stabbed the man multiple times.
The victim was transported to the Princess Alexandra Hospital in a critical condition but succumbed to his injuries on June 18.
The 17-year-old was previously charged with attempted murder, threatening violence, and possession of a knife in a public space.
His charge was upgraded to murder at Richlands Childrens Court today.
He is due to reappear on August 29.