Senator Fraser Anning has escaped charges for slapping Will Connolly after the 17-year-old cracked an egg on his head.
In a statement Victoria Police said they believed Senator Anning acted in "self-defence" and there was no reasonable prospect of conviction.
Connolly, who has been dubbed "Egg Boy", was issued with an official caution for his stunt.
He gained worldwide notoriety after footage emerged of him cracking an egg on Senator Anning's head after the New Zealand terror attack.
Afterwards, Senator Anning turned around and struck Connolly twice before he was tackled to the ground by a group of supporters.