Matlock Town FC midfielder Jordan Sinnott died in hospital after suffering a fractured skull and brain damage in an assault in the centre of Retford, Nottinghamshire, at about 2am on January 25.
Cameron Matthews, 21, pleaded guilty to manslaughter at an earlier hearing, admitting he administered the fatal punch.
After a trial at Nottingham Crown Court, Kai Denovan, of Collins Walk, Retford, was also found guilty of manslaughter, Nottinghamshire Police said.
Prosecutors said he “flew immediately into a rage” after the footballer joined in with what he believed to be the defendant’s “self-deprecating humour”.
Sean Nicholson, 22, of Beechways, Retford, admitted affray in connection with the same incident.
Nottinghamshire Police released CCTV footage which showed the final moments before Mr Sinnott was attacked – footage which led the three “to be brought to justice”.
During 22-year-old Denovan’s trial, the court heard that Matthews was “taking over” from Denovan who was “plainly hell-bent on trouble” – and who had allegedly punched Mr Sinnott twice in the face inside a pub called The Vine.
Prosecutor Michael Auty QC told the court Mr Sinnott was willing to apologise for any offence caused, but described Denovan, Matthews and Nicholson as a “pack hunting down and exacting retribution”.
Jurors heard that Denovan “followed rapidly behind” Mr Sinnott and two friends, Ben Bossons and Adam Towlson, into The Vine, before telling the victim he was a “good-looking lad” and would have no trouble “pulling girls” – unlike himself, who was “fat and ginger”.
“Yes I can see that,” Mr Sinnott replied, which the prosecution said provoked the attack.
Matthews, of Denman Close, Retford, hit Mr Sinnott “two or three times” after the violence spilled out into the street outside the pub.
Detective Chief Inspector Rob Routledge, who led the investigation, said: “Jordan was a talented and loved young man who had many promising years ahead of him.
“Matthews’ and Denovan’s actions in the early hours of 25 January cruelly took that future away from Jordan and changed his family’s lives forever. The response to Jordan’s death showed just how much he meant to those who knew him.
“I have been astounded by the courage, strength and integrity of Jordan’s family and friends throughout. They have inspired us all during many the long hours of this large and complex investigation.
“Nottinghamshire Police was tireless in conducting this large and complex investigation, and we were determined to hold Matthews and Denovan responsible for their actions. This meticulous work, including speaking to dozens of witnesses and trawling through hours of CCTV, has led to them being brought to justice.
“Life will never be the same for Jordan’s family, but I hope they will get some comfort from justice being served.”
All three men will be sentenced at the same court on July 31.
Jordan’s father Lee was born in Aldridge and went to play 40 times for the Saddlers in the 1980s. The 54-year-old also played for Rushall Olympic.
Lee went on to play for other clubs including Watford, Bradford City, Crystal Palace and Huddersfield Town.
After his playing career, he managed Port Vale as well as a number of non-league sides.