John Riley, 28, of Caernarfon was convicted by a jury on "overwhelming evidence" of inflicting grievous bodily harm on a 47-year-old man outside a pub in the town.
Judge Huw Rees at Caernarfon Crown Court told him he could have killed the man as a result of his anger.
As well as a broken skull, the victim suffered a bleed on the brain.
He will also now need a hearing aid following the attack.
North Wales Police Det Sgt Andy Davies said Riley was a "prolific offender" and his imprisonment would "bring a degree of relief and satisfaction to the whole community".
Judge Rees added there was a "complete lack of police presence" at the Maes on the night of the assault.
He called for the licensing authorities to be shown the CCTV footage and consider the suitability of the Morgan Lloyd pub having extended opening hours.
A "violent young man" from Gwynedd has been jailed for three years after a single punch broke his victim's skull.