Parents and children fled the shop in fear of their lives during the raid at Birstall Retail Park on December 12 last year.
Leeds Crown Court heard an off-duty police officer initially feared the attack to be a terror incident.
The gang of Romanian nationals threatened members of store staff before stealing £16,000 worth of iPhones, iPads and laptop computers.
The youngest member of the gang appeared before the court to be sentenced for the offences.
Bashir Ahmed, prosecuting, said the boy, who cannot be identified for legal reasons, also carried out a robbery on an 11-year-old girl in Harehills in which he stole her mobile phone and sold it for £50.
The defendant was involved in a further theft of four mobile phones from a Tesco store in Doncaster, causing damage worth £4,800.
He pleaded guilty to two offences of robbery, theft, criminal damage and making threats with a blade.
An adult male has already been jailed for 54 months over his involvement in the Currys PC World robbery.
Two 16-year-old males were made the subject of youth rehabilitation orders when they appeared before the court in February.
Sentencing of the 14-year-old was adjourned earlier this year to allow an investigation into whether he may have been trafficked into the UK..
The defendant has been in custody since he was arrested on the day of the offence.
He was released after being made the subject of youth referral order after the court heard it was likely that he had been the victim of modern slavery.
The boy had described being taken to the retail park and given a knife before being told he would be left there if he refused to take part in the robbery.
The court heard the boy waved the knife around in front of customers who panicked and were extremely scared.
The weapon was described as looking similar to a machete.
Sentencing the youngster, Judge Simon Phillips QC said: "The threats you shouted indicated that you knew how to threaten and swear in the English language.
"The victims were extremely fearful of being stabbed.
"Customers were panicking and evidently terrified.
"Some tried to hide their children.
"It was entirely foreseeable that in the month leading up to Christmas there would be a number of families and children present.
"An off-duty police officer who was shopping with her young son initially thought this was a terror attack."
The store manager described in a victim statement to the court how staff had been referred for counselling due to the terror they had been subjected to
Judge Phillips told the youngster he would have been facing a tougher sentencing had it not been for a report by the National Referral Mechanism and youth offending officers stating that it was probable that he had been a victim of modern slavery.
The teenager was made the subject of 24-month youth rehabilitation order.
He was told he must abide but an electronically-monitored curfew for eight months.
He must also complete a 90-day activity requirement.
An order was also made banning him from leaving the boundaries of Leeds for three months.
The National Referral Mechanism (NRM) is a process set up by the Government to identify and support victims of trafficking in the UK.
It is a framework for identifying victims of human trafficking and ensuring they receive the appropriate protection and support.
The NRM is also the mechanism through which the Modern Slavery and Human Trafficking Unit collects data about victims.
This information aims to help build a clearer picture about the scope of human trafficking in the UK.