Matthew Paul Wiggins had pleaded not guilty in the NSW Supreme Court to murdering Darko Janceski, 32, and causing grievous bodily harm to his dad, Slobodan Janceski, six years ago.
Darko Janceski had been working on a car outside his family's Wollongong home in April 2012 when he was shot three times by a masked motorcyclist.
When his father ran outside to discover his dying son, he picked up a garden stake from the front yard and lunged at Wiggins, the Crown alleged.
But the former professional boxer suffered a broken nose, a shattered jaw and a fractured eye socket in an ensuing fight before the assailant fled - leaving his gun behind.
The father also knocked off the shooter's helmet and sunglasses and both items were later linked to Wiggins through DNA testing.
The prosecution alleged Wiggins carried out the execution to avenge his missing friend, Goran Nikolovski.
Nikolovski, along with Darko Janceski, were allegedly standover men for people involved in the drug trade.
A jury was discharged in December after failing to reach verdicts but on Wednesday a second jury found Wiggins guilty of both charges.
Earlier in 2017, a first trial was aborted for legal reasons.
Wiggins will face a sentencing hearing on June 28.