The 42-year-old victim lost two pints of blood in the attack after being followed into the cinema car park and attacked by Arjan Sandhu with the "fearsome weapon" in an unprovoked attacked.
Sandhu, 18, had been drinking spirits as he watched Blue Story, a film which depicts gang violence.
Two cinema chains took the decision to pull the film from its UK venues last November following a 100-strong machete brawl at a screening in Birmingham.
Leeds Crown Court heard Sandhu attacked his victim in the car park of the Odeon cinema, in Huddersfield, on November 22 last year.
Carmel Pearson, prosecuting, said Sandhu went to the screening of the film with a group of friends and was sat near the victim, who was with a 14-year-old boy.
Miss Pearson said the victim works for a youth project which helps vulnerable males.
He had taken the 14-year-old to watch the film as part of his work acting as a mentor to the youngster.
Miss Pearson said Sandhu and the victim knew each other and spoke briefly before the film started.
Sandhu approached the man in the car park after the film as he was walking to his car with the 14-year-old boy.
Miss Pearson said: "He (the victim) described to the police that the defendant looked like his eyes were empty - black eyed - and suspected he there was going to be some sort of confrontation."
Sandhu began asking the man about where he lived. The victim became concerned for the safety of the 14-year-old boy and shielded him from the defendant.
The victim noticed a bulge in Sandhu's jacket and saw him take out a machete which had a 12-inch blade.
Miss Pearson said: "In his own mind he thought the matter could be resolved.
"He described how he had known him (Sandhu) since he was a young boy, watched him grow up.
"He thought things would be avoided. The defendant then fully produced the machete and waved it towards him in a half-chop motion.
"He didn't move back as he did not want him to think he was acting defensively or aggressively"
Sandhu then raised the weapon and hit the man to the body with it
The blow struck him under the left arm.
The victim tried to grab the weapon but stopped when he realised other people with Sandhu were approaching and he did not want to make the situation worse.
Sandhu put the machete back in a sheath and was restrained by other people.
The cinema car park was busy with families heading home at the time of the incident .
The attack was witnessed by a ten-year-old girl.
An ambulance was called when the victim realised he had suffered a serious wound.
The prosecutor said the wound needed stitches and he lost two pints of blood.
Sandhu handed himself in to the police three days after the attack but made no comment when interviewed.
Miss Pearson said the victim had suffered nightmares since the incident and had lost trust in people.
He had to take iron tablets after the attack because of the amount of blood he lost.
Sandhu, of Skelton Crescent, Crosland Moor, Huddersfield, pleaded guilty to unlawful wounding and possessing an offensive weapon.
He was sent to a young offender institution for 30 months.
Anastasis Tassou, mitigating, said Sandhu had written to the victim to apologise because he respected him for helping him when he was younger.
Mr Tassou said: "This is a tragic case. He has never come to the attention of the authorities before.
"One is really at a loss to try to explain how this possibly could have occurred.
"We in the criminal justice system are all too familiar with offences involving knives.
"It has become all too prevalent in our society.
"We are all too familiar with it becoming almost regular practice for young adults, teenagers, in particular areas to be carrying knives around with them as a matter of course, perhaps because of their membership of a gang.
"Mr Sandhu is not one of those defendants."
Mr Tassou said Sandu could not explain why he carried out the attack.
He said: "The only thing he can think of is that it coincided with his first experience of alcohol. It had never passed his lips before.
"He had gone out to watch a film popular among those of his age with a large group of adults when he had only recently passed the threshold of his eighteenth birthday and was encouraged to take alcohol.
"He took brandy and some other sort of spirit."
Sentencing Sandhu, Judge Simon Phillips QC said: "A particularly concerning feature of this case is the mindset that you displayed when being present and armed with a machete at a public cinema.
"Families were present as children's films were being shown.
"It is a tragedy to see a young man of your age, with your life in front of you, highly regarded by others, in the predicament that you find yourself.
"It is a personal tragedy not just for you but for your family."
Vue Cinemas and Showcase Cinemas in the UK decided to stop screening the film after an outbreak of violence during the film being shown at a cinema in Birmingham.
Showcase resumed screenings a few days later.
Police were called to Star City in Birmingham on Saturday November 23 following reports of youths with machetes.
Five teenagers were arrested following the trouble, including a 13-year-old girl.
Blue Story focuses on two friends from different south London postcodes, on rival sides of a street war.
It is rated 15 for very strong language, strong violence, threat, sex, and drug misuse.
Teen attacked charity worker with machete outside Yorkshire cinema after watching Blue Story gang film