A man accused of killing a teenage boy because he wanted to show he "owned" a Sydney suburb has been found guilty of murder.

Mosa Julius Mbele showed no reaction as the jury handed down its guilty verdict at the Supreme Court on Friday following a day and a half of deliberations.

Mbele was charged with murdering the 16-year-old, who can't be named for legal reasons, at Bankstown train station in Sydney's southwest on May 25, 2011.

He had pleaded not guilty on the grounds of self defence.

In her closing submissions earlier this week, Crown Prosecutor Nanette Williams told the jury they should have no doubt Mbele was the aggressor as he had armed himself with a knife.