James Arthur Collinson, 38 of Bridlington, punched 59-year-old John Glenn twice in Scarborough on September 1 last year.
Arthur first punched Mr Glenn inside the Golden Last pub at about 6pm following an altercation.
He then punched Mr Glenn again as he was leaving the pub.
The punch knocked Mr Glenn unconscious.
Ambulance crews attempted to resuscitate Mr Glenn before he was taken to Scarborough District Hospital.
Mr Glenn was then placed into a medically induced coma.
He did not respond to treatment and died on September 27.
Collinson was jailed at Leeds Crown Court on Friday, February 14 after pleading guilty of the manslaughter of Mr Glenn.
He has been jailed for six years with an extended period of four years on probation.
Investigating Officer, North Yorkshire Police’s Detective Inspector Jonathan Sygrove, said:
“Collinson has a long history of violence and assault and his sentence clearly reflects the seriousness of his most recent offence which resulted in the tragic loss of a man’s life.
"His actions have caused a huge amount of pain for John Glenn’s family and this is something they will have to deal with for the rest of their lives.”
Mr Glenn’s family ask that their privacy is respected.