Footage shared by the police shows how the men assaulted three American tourists in a street in west London last November while stealing a £100,000 watch.
The father of the man who owned the watch can be seen trying to push back the attackers before one of the thugs threatens him with a knife.
Two men were convicted on October 5 for their involvement in the attack and robbery.
Thomas Lenaghan, 23, of Fulham in west London, and Ronnie Fitzgerald, 20, of Romford in east London, pleaded guilty to conspiracy to rob, threatening a person with a bladed article in a public place, possession of a stun gun and threatening a person with a stun gun.
John Stovell, 50, in Hammersmith, pleaded guilty to handling stolen goods and assisting an offender.
All three men will be sentenced on December 9.
The footage shows three men crossing Pavilion Road in Chelsea on November 16, 2021, when they were approached by a group of men in balaclavas.
One of the victims was pushed to the ground and hit from behind with a stun gun, before the robbers took his £100,000 Rolex watch.
The victim's father was threatened with a knife, which cut through his coat but did not injure him.
The men aimed the stun gun at the third victim, a woman, and forced her to hand over her £200 watch.
The robbers then sped off in a stolen Jaguar.
The men were difficult to identify at first, because they had their faces covered and were not wearing distinctive clothes.
The Jaguar was also stolen and had false licence plates, which made it hard to track down.
Officers were eventually able to find a sticker on the bottom-right corner of the windshield.
They then asked owners of Jaguars that had recently been stolen if they had any distinguishing features - and one said they had a sticker as a parking permit for their child's school.
That let police track the car further and find footage where the men's faces were exposed, leading eventually to their arrests.
DC Robert Rodak, who worked on the investigation, said: “This was a shocking and violent robbery which understandably left the victims shaken and feeling incredibly fortunate they did not suffer more serious injury.
“Everyone should be able to walk through our streets unaffected by this type of crime and that is why we are doing everything we can to take offenders like Lenaghan, Fitzgerald and Stovell off our streets.
“This conviction was a result of a joint effort where our local team was assisted by the specialist skills of the Flying Squad to catch those responsible. Working together we will continue to target and relentlessly pursue robbers who commit violent crime in London.”