Max Maguire died in October 2021 from stab wounds to the chest outside the club in Lymington.
Draven Jewell, 21, was found not guilty of murder but convicted of the manslaughter of a fisherman.
On October 22, 2021, he was on trial at Winchester Crown Court for the death of a father-of-one.
He was also acquitted of the attempted murder of Mr Maguire’s friend, Luke Gray, but found guilty of wounding him. An additional wounding charge was dropped against him.
Jewell was also found guilty of wounding another friend, Georgia Hole, but was acquitted of another wounding charge.
He also admitted to possessing an offensive weapon, a Huusk chef’s knife.
Garon Jewell, 19, was formally acquitted of his role in the incident after the prosecution presented no evidence.
According to the court, a fight erupted after a disagreement between two groups in the club after one person challenged Garon Jewell’s age.
Tensions also rose when Draven Jewell discovered and brought to the club a nitrous oxide canister that he refused to sell to the other group, which included the three victims.
Mr Gray, 23, suffered two serious lower back wounds that necessitated emergency hospital treatment, while Ms Hole, 23, suffered a less serious injury to her chest.
“Max Maguire died within moments from a wound he received to the left side of his chest, a knife wound, this had penetrated his lung and damaged a major artery internally and caused catastrophic and non-survivable injuries,” prosecutor Adam Feest QC said.
Draven Jewell, of Lymington, claimed he was acting in self-defense because he was afraid his brother would be killed.