Horrobin punched 24-year-old Lewis Siddall, from Skellow, in a Doncaster bar in August. Mr Siddal was later found dead at his home.
Justice Holgate handed Blue Horrobin of Highfield Road, Askern an 11-year sentence, including a three year extension, after he was found guilty of one count of manslaughter last month.
Horrobin was given the three year extension to his sentence, after Justice Holgate deemed he posed a ‘high risk of serious harm’ to the public, following the unprovoked attack on 24-year-old Lewis Siddall on August 13, 2015 The extension was also awarded due to behaviour exhibited with Horrobin’s previous convictions, one of which saw the former bookmaker fracture a man’s cheek bone in three places during an unprovoked attack.
Horrobin, who will not be eligible for parole until he has served at least two-thirds of his sentence, remained silent as he was sent to prison. A woman in the public gallery sobbed, as Horrobin was taken away to begin his sentence.
A post-mortem examination found Mr Siddall, a PE teacher, died from a head injury.
Horrobin was seen landing a single punch to Lewis’s head inside the VDKA bar at around 23:00 GMT on 11 August.
CCTV and witness accounts led police and prosecutors to believe the assault was unprovoked.
Det Ch Insp Steve Handley said: “Lewis was killed as the result of an unprovoked and senseless act of violence when he was simply out enjoying himself with some friends.
“This was an avoidable death and shows the devastating effect one punch can have on the lives of the victim, their family and friends.”
“This could have been entirely avoided, had Horrobin made a different decision not to lash out with his fists, Lewis would still be alive and well today.”