Residents fought to save the victim after the schoolboy attacked him with a knife on Whingate, Armley.
A court heard horrific details of the attack which took place when the dad challenged the boy over the theft of his son's bike.
The teenage defendant, now aged 16, was handed an extended custodial sentence of eight years after being assessed as posing a serious danger to the public.
Andrew Epsley, prosecuting, told Leeds Crown Court the attack happened on May 14 this year when the dad approached a group of youths over the bike theft.
Mr Epsley said the victim's son had been pulled off his bike by a group of youth weeks earlier and had it stolen from him.
The 32-year-old dad approached the group when his son recognised them in the street and pointed out the defendant as the youth responsible for taking the bike.
His son and and daughter were nearby as he approached the group and accused the defendant of stealing the bike.
The prosecutor said the teenager had a knife in his rucksack.
The dad then walked away from the group and told them he was not going to get involved.
As he walked away he felt a pain in his back and thought he had been punched.
He turned around and grabbed the teenager before punching him to the face and taking him to the ground.
The defendant bit the man's finger during the struggle.
Mr Epsley said people in the street approached the man and told him he was bleeding and looked "in a bad way."
The court heard the man then began struggling to breathe and felt pain in his chest.
Police officers and paramedics arrived at the scene to find the victim covered in blood as members of the public tried to help him.
The teenager was detained nearby and was placed in handcuffs.
He told officers: "I didn't f****** stab him."
The victim was taken to Leeds General Infirmary with three deep puncture wounds to his back and side.
The knife wounds caused a punctured lung and damage to his liver and spinal cord.
Mr Epsley said the injuries were life threatening.
The victim left hospital after a week but was rushed back in for more surgery as his diaphragm had also been perforated but went diagnosed when first admitted to hospital.
The teenager, who cannot be identified, was initially charged with attempted murder.
Victoria Smith-Swain, mitigating, said the teenager was sorry for what he had done and apologised for bringing shame on his family.
Ms Smith-Swain said the defendant has been in custody since the incident and his family have moved away from Leeds.
The barrister said her client had not planned the attack, saying: "(The defendant) had been accused of a crime he had not committed and took umbrage to the accusation."
Ms Smith-Swain said there was evidence the youngster had been involved with more sophisticated criminals and may have been the victim of modern day slavery.
She added that the teenager had himself previously been the victim of a knife attack.
Judge Simon Batiste said: "If one is the victim of a stabbing, one knows how dangerous that is. It does not give someone carte blanche to say they can carry knives around."
The teenager was told he must serve a custodial term of five years followed by a further three years on licence.
Judge Batiste told the defendant: "This is an offence of the absolute most serious type for a first occasion to come before a court.
"You stabbed a man repeatedly.
"I am satisfied that in order to provide protection to the public I must pass an extended sentence of imprisonment for public protection."
After the case, Detective Inspector James Entwistle, of Leeds District CID, said: “This was an appallingly violent attack on the victim which could have very easily had a more tragic outcome.
“The fact that someone so young was responsible is particularly concerning, and the court has imposed a lengthy sentence that recognises the seriousness of this offence.
“This incident clearly highlights the very serious consequences of young people carrying knives, which is an issue that the police will continue to proactively target in our communities alongside our partner agencies.
“We don’t underestimate the traumatic effect this incident has had on the victim and his family and we hope they can find some reassurance in knowing that the person responsible has had to answer for his actions.”