Lee Clarkson lost his temper and was like a "raging bull" when he punched Christopher Skitt in the face, knocking him unconscious outside the Elephant pub, Leeds Crown Court heard.
Clarkson, 31, then repeatedly stamped on Mr Skitt's face, causing multiple facial fractures.
Mr Skitt had to undergo surgery to insert screws and plates to repair his right cheekbone.
He also suffered a broken collarbone and extensive injuries to his right ear, which was so badly damaged part of it was hanging off and had to be re-attached with stitches.
Clarkson, who has no previous convictions, admitted causing grievous bodily harm with intent.
Recorder Brain Cox QC jailed Clarkson for three-years-and-four-months.
The court heard Clarkson was at the Elephant pub with other family members on October 19 last year following the funeral of his grandfather, a retired police officer.
Prosecutor, Duncan Ritchie said Clarkson, of Racca Green, Knottingley, was drunk and was stood outside the pub at around 5.30pm when a row erupted.
Mr Ritchie said Clarkson and his cousin Michelle Edwards - Christopher Skitt's stepdaughter - ended up on the floor.
The court heard Mr Skitt was told there was an argument and came out of the pub to see his stepdaughter on the ground.
Mr Ritchie said: "It was apparent that the defendant had completely lost his temper. Mr Skitt described him as like a raging bull."
Family members restrained Clarkson before he broke free and punched Mr Skitt in the face, knocking him unconscious.
Mr Ritchie said Clarkson then stamped on Mr Skitt's head at least four times, adding: "One of Mr Skitt's teeth came out and that was seen by a number of people."
Mitigating, Matthew Harding said: "It was his grandfather's funeral. A man he describes as being like a father to him."
Mr Harding said Clarkson's grandfather was a retired police officer, adding: "He became emotional, upset and angry.
"He doesn't know what has led him to behave in an appalling and disgusting manner."
Jailing Clarkson, Recorder Cox told him: "Whilst he was prone on the ground you inflicted very serious injury to him, including fractures to the right cheekbone."